Portable wastewater treatment method

ABSTRACT

A portable wastewater treatment system for recycling an aqueous surfactant solution utilized in a parts washer assembly for cleaning parts. The system including a contaminated solution storage tank, a treated solution storage tank, and a portable wastewater treatment apparatus wherein contaminated aqueous surfactant solution is collected in the contaminated solution storage tank, withdrawn from the contaminated solution storage tank, injected with air and passed into a mixing zone where the mixture is sprayed with water. The treated solution in the mixing zone is passed into a quiescent zone where light sludge is passed to the top of the quiescent zone and heavy sludge is passed to the bottom of the quiescent zone, the treated wastewater being disposed between the light sludge and the heavy sludge and the treated wastewater being passed from the quiescent zone into a discharge zone where the treated wastewater is discharged therefrom. The heavy sludge is selectively discharged from the quiescent zone. The light sludge is passed from the quiescent zone into a light sludge bin where the light sludge is selectively discharged therefrom. The treated solution is passed to the treated solution storage tank to provide a recycled supply of treated cleaning solution.

RELATED REFERENCES

This application is a continuation of U.S. application Ser. No.08/300,686 entitled "PORTABLE WASTEWATER TREATMENT METHOD" filed Sep. 2,1994, now U.S. Pat. No. 5,534,159, which is a continuation-in-part ofU.S. application Ser. No. 08/100,876 entitled "WATER TREATMENT METHODSAND APPARATUS" filed Aug. 1, 1993; which is a continuation of U.S.application Ser. No. 07/969,615 entitled "WASTEWATER TREATMENT APPARATUSAND METHOD" filed Oct. 30, 1992, now U.S. Pat. No. 5,288,787, issuedFeb. 22, 1994; which is a continuation of U.S. application Ser. No.07/616,583 filed Nov. 21, 1990, now U.S. Pat. No. 5,173,184, issued Dec.22, 1992.

FIELD OF THE INVENTION

The present invention relates generally to wastewater treatment systems,and more particularly, but not by way of limitation, to a portablewastewater treatment system for recycling an aqueous surfactant solutionused for cleaning parts in a parts washer assembly wherein the aqueoussurfactant solution is contaminated with residue removed from partsduring the cleaning of same by the aqueous surfactant solution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective, partial schematic rear view of awastewater treatment apparatus constructed in accordance with thepresent invention.

FIG. 2 is a partial perspective, partial schematic front view of aportion of the wastewater treatment apparatus of FIG. 1, particularlyshowing the two treatment cells.

FIG. 3 is a sectional view of a typical treatment cell in the wastewatertreatment apparatus shown in FIGS. 1 and 2 and schematically showing thecontrols for discharging sludge from the wastewater treatment apparatus.

FIG. 4 is an elevational view of the front side of the typical treatmentcell shown in FIG. 3.

FIG. 5 is an elevational view of a portion of the treatment cell shownin FIG. 3.

FIG. 6 is a partial perspective, partial diagrammatic view of a rake forremoving light sludge from the treatment cell shown in FIG. 3.

FIG. 7 is a perspective, diagrammatic view of the drying zone of thewastewater treatment apparatus showing where the sludge removed from thetreatment cells in the wastewater treatment apparatus is dried.

FIG. 7A is a schematic view of the conveyor belt in the drying zoneshowing a spray bar for removing sludge from the openings in theconveyor belt.

FIG. 8 is a schematic view of a portable wastewater treatment systemconstructed in accordance with the present invention illustrating thesystem operably connected to a parts washer assembly.

FIG. 9 is a partially schematic, partially perspective view of asolution storage tank assembly constructed in accordance with thepresent invention.

FIG. 10 is a perspective rear view of a portable wastewater treatmentapparatus constructed in accordance with the present invention.

FIG. 11 is a partially cutaway, elevational view of the portablewastewater treatment apparatus.

FIG. 12 is an elevational view of the portable wastewater treatmentapparatus.

FIG. 13 is an elevational view of a portable cart having a pump anddisposal container disposed thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Shown in FIGS. 1 and 2 and designated by the general reference numeral10 as a wastewater treatment apparatus constructed in accordance withthe present invention. In general, wastewater is passed into tanks 12(FIG. 1) by way of a conduit 14 (FIG. 1). The wastewater is passed fromthe tanks 12 through a conduit 16 (FIGS. 1 and 3) into a first treatmentcell 18 (FIGS. 1, 2, 3 and 4). A pump 20 (FIG. 1) is interposed in theconduit 16 for pumping the wastewater into the first treatment cell 18.

The wastewater is treated in the first treatment cell 18. The treatedwastewater is discharged or passed from the first treatment cell 18 andpassed into a second treatment cell 22 (FIGS. 1, 2, 3 and 4) by way of aconduit 24 (FIGS. 1 and 3). A pump 26 (FIG. 1) being interposed in theconduit 24 for pumping the treated wastewater from the first treatmentcell 18 into the second treatment cell 22.

The wastewater is treated again in the second treatment cell 22 and thetreated wastewater is passed or discharged from the second treatmentcell 22 by way of a conduit 28 (FIGS. 1 and 3). A pump 30 (FIG. 1) isinterposed in the conduit 28 for pumping the treated wastewater from thesecond treatment cell 22.

The first and the second treatment cells 18 and 20 are identical inconstruction and operation. A typical treatment cell 18 or 20 is shownin greater detail in FIG. 3. The treatment cell 18 or 20 includes ahousing 32 (FIGS. 3 and 4) having a top 34 (FIGS. 3 and 4) and a bottom36 (FIGS. 3 and 4). The housing 32 encompasses and defines an internalchamber 38 (FIG. 3).

A baffle 40 (FIG. 3) is connected to the housing 32 and supported withinthe internal chamber 38. The baffle 40 cooperates with a portion of thehousing 32 to define a mixing zone 42. A baffle 41 is disposed in theinternal chamber 38 near the baffle 40 for defining a path for thewastewater to be passed from the mixing zone 42.

A baffle 44 (FIGS. 3 and 5) is disposed in the internal chamber 38 nearone end of the housing 32, opposite the end of the housing forming themixing zone 42. The baffle 44 cooperates with a portion of the housing32 to define a discharge zone 46 in the internal chamber 38. A baffle 48(FIG. 3) is disposed in the internal chamber 38 and positioned near thebaffle 44 for defining a path through which the treated wastewaterpasses into the discharge zone 46. The area in the internal chamber 38between the baffle 48 and the baffle 40 or, in other words, between themixing zone 42 and the discharge zone 46 defines a quiescent zone 50(FIG. 3).

The wastewater passes into the mixing zone 42 via either the conduit 16or the conduit 24 depending on whether the treatment cell is the firsttreatment cell 18 or the second treatment cell 22. Prior to passing thewastewater into the first treatment cell 18 and prior to passing thewastewater into the second treatment cell 22, compressed air from an airsupply 54 (FIG. 3) is introduced into the wastewater. The compressed airis introduced into the wastewater in an amount sufficient so that largeair bubbles are formed in the wastewater in the mixing zone of thetreatment cell 18 or 22.

A water supply 56 (FIG. 3) is connected to spray nozzles 58 (FIG. 3)positioned above the liquid level in the mixing zone. Air from an airsupply 60 (FIG. 3) is introduced into the water prior to the water beingsprayed into the mixing zone via the nozzles 58.

The wastewater in the mixing zone is sprayed with water from the nozzles58. The nozzles 58 are positioned above the liquid level of thewastewater in the mixing zone 42. The water sprayed onto the surface ofthe wastewater in the mixing zone 42 so that the sprayed water contactsthe large air bubbles in the mixing zone 42 and substantially reducesthe size of the large air bubbles in the mixing zone.

The wastewater is passed from the mixing zone 42 into the quiescent zone50 as indicated by the arrow 62 in FIG. 3. In the quiescent zone 50,heavy sludge is permitted to settle to the bottom of the housing 32 intoa heavy sludge area 64 (FIG. 3) formed in the internal chamber 38 nearthe bottom 36 of the housing 32. More particularly, the bottom 36 of thehousing 32 comprises two cone shaped members 66 and 68 (Figures, 1, 3and 4). The cone shaped members 66 and 68 surround and define the heavysludge area 64 with the cone shaped members 66 defining a heavy sludgearea 64a (FIG. 3) and the cone shaped members 68 defining a heavy sludgearea 64b (FIG. 3).

In the quiescent zone 50, light sludge is permitted to rise to the upperliquid level of the wastewater in the quiescent zone 50 forming anddefining a light sludge area 70 (FIG. 3) positioned near the top of theliquid level in the quiescent zone 50. The treated liquid portion of thewastewater in the quiescent zone 50 is disposed between the heavy sludgearea 64 and the light sludge area 70 and this treated wastewater ispassed from the quiescent zone 50 upwardly between the baffles 44 and 48and discharged through an opening in the baffle 44 into the dischargezone 46 as indicated by the arrow 72 in FIG. 3. The treated wastewateris passed from the discharge zone 46 through either the conduit 24 intothe second treatment cell 22 or through the conduit 28 out from thesecond treatment cell 22 depending upon whether the treatment cell shownin FIG. 3 is the first treatment cell 18 or the second treatment cell20.

It should be noted that, although only two treatment cells 18 and 22 areshown in FIGS. 1 and 2, the wastewater treatment apparatus 10 of thepresent invention could include additional treatment cells allconstructed like the treatment cell shown in FIG. 3 connected in serieswith the first and the second treatment cells 18 and 20 shown in FIGS. 1through 3 and described before. It also should be noted that thewastewater treatment apparatus 10 may include only the first treatmentcell 18 and, in this event, the treated wastewater is discharged fromthe first treatment cell 18 and passed to an area for removal or to adrying zone as will be described below.

The wastewater treatment apparatus 10 as described before is shown anddescribed in detail in Applicant's co-pending application, U.S. Ser. No.07/969,615, titled WASTEWATER TREATMENT APPARATUS AND METHOD, filed,Oct. 30, 1992; which is a continuation of Applicant's U.S. Pat. No.5,173,184, titled WASTEWATER TREATMENT APPARATUS AND METHOD, issued Dec.22, 1992, and the disclosures in this co-pending application and thisissued patent hereby specifically are incorporated herein by reference.

It should be noted that in lieu of the two cone shaped members 66 and68, a single cone shaped member could form the bottom 36 of the housing30 thereby providing only one discharge area for the heavy sludge or twoor three discharge areas could be provided in the single cone shapedmember.

A discharge conduit 80 (FIGS. 1, 3 and 4) is connected to the coneshaped member 66 and the opening through the discharge conduit 80 is influidic communication with the heavy sludge area 64a. The heavy sludgein the heavy sludge area 64a is passed through the opening in thedischarge conduit 80 and discharged from the heavy sludge area 64aduring one aspect of the operation as will be described below.

A valve 82 (FIG. 3) is interposed in the conduit 80. The valve 82 has anopened position and a closed position. In the opened position, the valve82 establishes fluidic communication through the conduit 80 fordischarging the heavy sludge from the heavy sludge area 64a through theconduit 80 for transferring the heavy sludge to a disposal area or adrying zone as will be described below. The valve 82 is a solenoid orelectrically operated type of valve and includes a valve controller 84(FIG. 3) adapted to receive an electrical signal by way of a signal path86 (FIG. 3) from a system control 88 (FIG. 3). The system control 88 isconstructed and adapted to provide a signal via the signal path 86 tocause the valve 82 to be opened for predetermined discharge times and atpredetermined discharge intervals for controlling the discharge of theheavy sludge from the heavy sludge area 64a.

A discharge conduit 89 (FIGS. 1, 3 and 4) is connected to the coneshaped member 68 and the opening through the discharge conduit 89 is influidic communication with the heavy sludge area 64b. The heavy sludgein the heavy sludge area 64b is passed through the opening in thedischarge conduit 89 and discharged from the heavy sludge area 64bduring one aspect of the operation as will be described below.

A valve 90 (FIG. 3) is interposed in the conduit 89. The valve 90 has anopened position and a closed position. In the opened position, the valve90 establishes fluidic communication through the conduit 89 fordischarging the heavy sludge from the heavy sludge area 64b through theconduit 89 for transferring the heavy sludge to a disposal area or adrying zone as will be described below. The valve 90 is a solenoid orelectrically operated type of valve and includes a valve controller 92(FIG. 3) adapted to receive an electrical signal by way of a signal path94 (FIG. 3) from the system control 88. The system control 88 isconstructed and adapted to provide a signal via the signal path 94 tocause the valve 90 to be opened for predetermined discharge times at apredetermined discharge intervals for controlling the discharge of theheavy sludge from the heavy sludge area 64b.

The baffle 44 in the treatment cell 18 or 22 is shown in greater detailin FIG. 5. The baffle 44 has an upper end 96 and a lower end 98. Thelower end 98 is secured to the bottom of the housing 32 and the upperend 96 is positioned above the liquid level of the wastewater in theinternal chamber 38 of the housing 32. An opening 100 is formed throughthe baffle 44 and positioned near the upper end 96. The treatedwastewater passes through the opening 100 into the discharge zone 46.

As shown in FIG. 5, a cover plate 102 is supported below the opening 100and positioned about adjacent the baffle 44. The cover plate 102 issized to cover and substantially close the opening 100 during certainaspects of the operation as will be described in greater detail below.

As shown in FIG. 5, the cover plate 102 is supported by two pneumaticcylinders 104 and 106. In practice, the pneumatic cylinders 104 and 106each are connected to an air supply 108 via a conduit 110, a four waycontrol valve 114 and a conduit 111 or 112, respectively. The pneumaticcylinders 104 and 106 utilize two air lines, one for passing air intothe pneumatic cylinder 104 and 106 and each also includes a conduit forpassing air from the pneumatic cylinders 104 and 106.

As shown in FIG. 5, the control valve 114 having a valve controller 116is interposed in the conduit 110 for interrupting the communicationbetween the air supply 108 and the pneumatic cylinders 104 and 106 in aclosed position of the valve 114 and for establishing communicationbetween the air supply 108 and the pneumatic cylinders 104 and 106 in anopened position of the valve 114. The valve controller 116 operates toreceive an electrical signal via a signal path 118 (FIGS. 3 and 5) and,in response to receiving a signal via the signal path 118, the valvecontroller 116 opens the valve 114 establishing communication betweenthe air supply 108 and the pneumatic cylinders 104 and 106. The signalpath 118 is connected to the system control 88.

Each of the treatment cells 18 and 22 also includes a rake 126 (shown inFIG. 3 and shown in more detail in FIG. 6). The rake 126 comprises anelongated solid bar 128 (FIG. 6) having a rubber flap 130 (FIG. 6)attached to and extending a distance from the bottom of the bar 128.

A chain 132 (FIG. 6) is supported in the internal chamber 138 on twosprockets 134 and 136 (FIG. 6). Another chain 138 (FIG. 6) is supportedin the internal chamber 38 on two sprockets 140 and 142. The chain 132is spaced a distance from the chain 138 and the chains 132 and 138extend generally along the opposite sides of the housing 32 and aredisposed near the top 34 of the housing 32. The opposite ends of the bar128 are connected to the respective chains 132 and 138. The chains 132and 138 are positioned in the internal chamber 38 for supporting the bar128 and the rubber flap 130 connected thereto near the liquid level ofthe wastewater in the quiescent zone 50 or, more particularly, toposition a portion of the bar 126 and the rubber flap 130 in the lightsludge area 70.

A DC gear motor 144 (FIG. 6) is connected to the sprocket 134 fordrivingly rotating the sprocket 134 thereby drivingly moving the chain132 connected thereto. The movement of the chain 132 causes the bar 128and the rubber flap 130 connected thereto to be moved following themovement of the chain 132 which also causes the chain 138 to be rotatedon the idler sprockets 140 and 142. The DC motor 144 is connected to thesystem control 88 via a signal path 146 (FIGS. 3 and 6).

In a non-operating position, the chains 132 and 138 are driven toposition the bar 128 and the rubber flap 130 connected thereto near oradjacent one side of the treatment cell 18 or 22.

A light sludge bin 148 (FIGS. 2 and 4) is connected to one side of thehousing 32 and an upper end 150 of the light sludge bin 148 ispositioned near the open top 34 of the housing 32. The light sludge bin148 has a cone shaped lower portion. A discharge conduit 152 (FIG. 4) isconnected to a lower end of the light sludge bin 148 and positioned sothat the opening in the conduit 152 is in fluidic communication with theinterior space (not shown) in the light sludge bin 148.

A control solenoid type valve 154 (FIG. 6) is interposed in thedischarge conduit 152. The control valve 154 has a valve controller 156(FIG. 6) which is a adapted to receive an electrical signal via a signalpath 158 (FIGS. 3 and 4) from the system control 88.

The control valve 154 has an opened position and a closed position. Inresponse to receiving a signal from the system control 88, the valvecontroller 156 causes the control valve 154 to be opened therebyestablishing fluidic communication through the discharge conduit 152 andpermitting light sludge in the light sludge bin 148 to be dischargedtherefrom.

The wastewater treatment apparatus 10 is constructed so that thedischarge from the heavy sludge areas 64a and 64b in each of thetreatment cells 18 and 22 is controlled by the system control 88 and sothat the discharge of the light sludge from the light sludge bin 148also is controlled via the system control 88. In operation and in aparticular system, one may find that heavy sludge will build up quickerin one or more of the heavy sludge areas 64a and 64b of the treatmentcells 18 or 22 and the system control 88 is adapted so that thedischarge of the heavy sludge from the heavy sludge areas 64a and 64b ofeach of the treatment cells 18 and 22 is individually controllable.

In operation, the various discharge times are preset in the systemcontrol 88. At the predetermined discharge times, the system control 88outputs a signal on the signal paths 86 and 94 and in response to suchsignals, the valve controllers 84 and 94 operate to open the controlvalves 82 and 90 thereby causing heavy sludge to be discharged throughthe discharge conduits 80 and 89 of the treatment cells 18 and 22. Asnoted before, the discharge times for discharging the heavy sludge inthe heavy sludge areas 64a and 64b of the treatment cells 18 and 22 allcould be different. The signals outputted by the system control 88 causethe respective valve controllers 84 and 92 to maintain the controlvalves 82 and 90 in the opened position for predetermined dischargeintervals of time. Again, the predetermined discharge intervals of timecan be the same or different for discharging the heavy sludge from theheavy sludge areas 64a and 64b of the treatment cells 18 and 22.

The system control 88 also is preset to output a signal on the signalpath 118 at a predetermined time and at predetermined time intervalsthereby causing the valve controller 116 to open the respective controlvalve 114 thereby establishing communication between the air supply 108and the respective pneumatic cylinders 104 and 106. The pneumaticcylinders 104 and 106 cause the cover plate 102 to be moved upwardly toa position wherein the cover plate 102 closes or partially closes theopening 100 in the baffle 44. The closing or partial closing of theopening 100 by the cover plate 102 causes the liquid level or, moreparticularly, the light sludge level in the light sludge area 70 in thequiescent zone 50 to rise toward the top 34 of the housing 32 to aposition wherein the rake 126 is disposed in and below the upper levelof the light sludge in the light sludge area 70.

Simultaneously with the output of the signal to the valve controller 116along signal path 118, the system control 88 outputs a signal on thesignal path 146 to the DC gear motor 144 energizing the DC gear motor144 and causing the sprocket 134 to be drivingly rotated. In response tothe driving rotation of the sprocket 134, the chain 132 is drivinglyrotated thereby moving the rake 126 across the top of the quiescent zone50. The rake engages the light sludge in the light sludge area 70 andmoves the engaged light sludge causes the engaged light sludge to bepassed into the opening in the light sludge bin 148.

In addition, the system controller 88 at predetermined discharge timesoutputs a signal on the signal path 158 thereby causing the valvecontroller 156 to open the control valve 154 for discharging lightsludge from the light sludge bin through the discharge conduit 152. Thesystem control 88 outputs the signal on the signal path 158 for causingthe light sludge to be discharged from the light sludge bin 148 forpredetermined discharge times and at predetermined discharge intervals.

The heavy sludge discharged from the heavy sludge areas 64a and 64b arepassed through a common conduit 170 (FIGS. 1 and 3) and passed intostorage tanks 172 (FIG. 7). The light sludge discharged from the lightsludge bins 148 are passed through a common discharge conduit 174 (FIG.7) and passed into the storage tanks 172.

In a preferred embodiment, the heavy sludge and the light sludge aredischarged into a single conduit (combined conduits 170 and 174) and apump (not shown) is interposed in said conduit for pumping the heavysludge and the light sludge into the storage tanks 172. Said pump (notshown) is automatically started when the valves 82 and 90 are opened.

The bottoms of the storage tanks 172 each are connected to a commondischarge conduit 176 (FIG. 7). Control valves 178 and 180 (FIG. 7) areinterposed in the discharge conduit 176 with the control valves 178 and180 each controlling the discharge from one of the storage tanks 172.The control valves 178 and 180 are solenoid by the valves and eachincludes a valve controller (not shown). The system control 88 isadapted to output signals on signal paths 182 and 184 (FIGS. 3 and 7)for controlling (opening and closing) the respective control valves 178and 180.

A pump 186 (FIG. 7) is interposed in the discharge conduit 176 forpumping the sludge from the storage tanks 172 in the opened position ofeither one or both of the control valves 178 and 180. The sludge ispumped into a distributor 188.

The distributor 188 comprises a housing 190 (FIG. 7) with an auger 192(FIG. 7) disposed at a lower end thereof. The lower end of the housing190 and the auger 192 disposed therein each are disposed above aperforated conveyor belt 194 (FIGS. 7 and 7A). The auger 192 functionsto distribute the sludge disposed in the distributor 188 over the top ofthe perforated conveyor belt 194.

The perforated conveyor belt 194 has a plurality of openings 196 (FIG.7) formed therethrough and spaced over the perforated conveyor belt 194.The perforated conveyor belt 194 is a continuous type of belt movablesupported on two drive shafts 197 and 198 (FIGS. 7 and 7A). The driveshaft 198 is connected to a motor 201 (FIG. 7A) for drivingly rotatingthe drive shaft 198 connected thereto and rotatingly moving theperforated conveyor belt 194 in a direction 202 (FIGS. 7 and 7A).

The sludge is distributed on the perforated conveyor belt 194 by thedistributor 188 and the sludge is moved via the perforated conveyor belt194 in the direction 202 to a position wherein the sludge is disposedunder an oven 204 which dries the sludge passing therethrough.Preferably, the oven 204 is a microwave type of oven for emittingmicrowave energy into the sludge for driving the water from the sludge.The water in the sludge passes through the openings 196 of theperforated conveyor belt 194. The dried sludge is passed from the oven204 and discharged into a dumpster 206 (FIG. 7) or other type ofcontainer.

Preferably, a scraper 207 (FIG. 7) is located at the end of the conveyorbelt 194. The scraper 207 blade is disposed about adjacent the conveyorbelt 194 for scraping the dried sludge from the conveyor belt 194.

A blower 208 (FIG. 7) may be disposed above the perforated conveyor belt194 for cooling the sludge dried by the oven 204 prior to dischargingthe sludge from the perforated conveyor 194 if desired. Further,additional heaters may be incorporated before and/or after the oven 204for further driving the water from the sludge.

The water driven from the sludge and passed through the openings 196 inthe perforated conveyor belt 194 passes into a drip pan 210 (FIG. 7)disposed below the perforated conveyor belt 194. The water is dischargedfrom the drip pan 210 via a discharge conduit 212.

The distributor 188, the perforated conveyor belt 194, the oven 204 andthe blower 208 cooperate to comprise a drying zone 214. In manyinstances, land fills will not take liquid sludge and the drying zone214 of the present invention is adapted to dry the sludge prior to thesludge being discharged into the dumpster 206 for transportation to awaste disposal site such as a land fill.

Diagrammatically shown in FIG. 7A is the perforated conveyor belt 194. Aspray bar 216 is disposed in the perforated conveyor belt 194 generallybetween the upper and the lower portions of the perforated conveyor belt194. The spray bar 216 sprays water onto the lower portion of theperforated conveyor belt 194 for forcing particles of sludge which mayhave become lodged in the openings 196 to be passed through ordischarged from the openings 196 and passed into the drip pan 210.

The valves have been described herein as being electrically operated. Itshould be noted that pneumatically or manually operated valves alsowould be suitable. Also, it should be noted that the motors describedherein could be AC or DC or air driven type of motors.

If the sludge has a heavy concentration of oil or if the sludge iswatery, materials can be added in the bins 172 for the thickening thesludge. Such thickening materials are well known such as diatomaceousearth or rice seed hulls or other similar materials. If highconcentration of metals in the sludge, lime also can be added in thebins 172. In these instances, a mixer may be added in the bins 172 formixing such materials with the sludge.

Embodiment of FIGS. 8-13

The degreasing of parts has been a problem which has long existed in thefield of parts cleaning and reclamation. Because of environmental andhealth considerations, aqueous based solutions have been proposed as areplacement for solvent based solutions in the degreasing of parts.However, problems exist in the use of aqueous based solutions fordegreasing of parts, such as poor cleaning performance, disposalproblems resulting from oil emulsions generated during the cleaningprocedure, the short effective life of the cleaning solutions, bacterialgrowth in the cleaning solution and excessive foaming of the cleaningsolution. Further, heavy metals contamination of the cleaning solutionpresent problems in the disposal of the spent aqueous cleaning solution.

Shown in FIG. 8 is a schematic illustration of a waste water treatmentassembly 220 constructed in accordance with the present invention whichsubstantially eliminates the above referenced problems associated withaqueous based solutions for degreasing and washing parts by enabling thewastewater to be effectively treated and reused. The wastewatertreatment assembly 220 is shown operably connected to a typical partswasher assembly 222 which includes a primary cleaning vessel 224 and areservoir 226 containing an aqueous surfactant cleaning solution(referred to hereinafter as cleaning solution). The reservoir 226 isconnected to the primary cleaning vessel 224 via a conduit 228 and aconduit 230. Conduit 228 serves as an inlet conduit for the cleaningvessel 224 and conduit 230 serves as an outlet conduit for the cleaningvessel 224 thereby enabling the cleaning solution to be continuouslycirculated through the cleaning vessel 224.

When the parts washer assembly 222 is in a parts cleaning cycle or mode,the cleaning solution is heated in the reservoir 226 by a heating device(not shown) which facilitates the dissolvement of the oil and greasecoating the fouled parts. The heated cleaning solution is pumped viaconduit 228 into the cleaning vessel 224 where it flows over the partspositioned therein. The cleaning solution circulates back to thereservoir 226 via conduit 230. The cleaning solution is circulatedthrough the cleaning vessel 224 for a predetermined length of time afterwhich the cleaned parts are removed from the cleaning vessel 224. Thecleaning solution contained in the parts washer assembly 222 can usuallybe reused several times before the cleaning solution becomescontaminated to the point where it no longer cleans parts effectivelyand thus needs to be replaced.

When the cleaning solution is spent and thus no longer effective forcleaning parts, the cleaning solution is withdrawn from the reservoir226 and passed to the wastewater treatment assembly 220. The wastewatertreatment assembly 220 includes a cleaning solution storage tankassembly 232 and a portable wastewater treatment apparatus 234.

Referring to FIGS. 8 and 9, the cleaning solution storage tank assembly232 includes a contaminated solution storage tank 236 and a treatedsolution storage tank 238 with each being provided so that when thecleaning solution which is being utilized in the parts washer assembly222 at a particular time becomes contaminated to the point it needs tobe replaced, the contaminated cleaning solution can be transferred tothe contaminated solution storage tank 236 and replaced with pretreatedor treated cleaning solution from the treated solution storage tank 238.This in turn enables the parts washer assembly 222 to be operated for anextended period of time without having to treat the contaminatedcleaning solution, and thus allow plant personnel to treat thecontaminated cleaning solution at their convenience without partscleaning operations being disrupted.

The contaminated solution storage tank 236 for receiving and holding thecontaminated cleaning solution is provided with a first fluid inlet 240,a second fluid inlet 242, a fluid outlet 244, and a solids outlet 246.The cleaning solution is transferred from the parts washer assembly 222to the contaminated solution storage tank 236 via the first fluid inlet240. The first fluid inlet 240 is connectable to the parts washerassembly 222 via a conduit 248 (FIG. 8) interconnecting the reservoir226 and the first fluid inlet 240 of the contaminated solution storagetank 236. The conduit 248 in FIG. 8 is shown to have a pump 250interposed therein for transferring the contaminated cleaning solution.Alternatively, a portable pump can be selectively coupled to the firstfluid inlet 240 and the fluid outlet of the reservoir 226 to transferthe contaminated cleaning solution in a manner to be discussed infurther detail hereinbelow.

In order that an operator can monitor the amount of cleaning solution inthe contaminated solution storage tank 236, the contaminated solutionstorage tank 236 is provided with a liquid level sensing unit 252 whichincludes a short probe 254 and a long probe 256, each electricallyconnected to a light 258 mounted on the top of the contaminated solutionstorage tank 236. The long probe 256 extends into the contaminatedsolution storage tank 236 such that the long probe 256 extends apredetermined distance from the bottom of the contaminated solutionstorage tank 236. The short probe 254 extends into the contaminatedsolution storage tank 236 a predetermined distance such that the shortprobe 254 energizes the light 258 when the contaminated cleaningsolution rises to the level of the short probe 254. The light 258 servesto inform an operator that the contaminated cleaning solution needs tobe treated before the cleaning solution is changed in the parts washerassembly 222 again. The contaminated solution storage tank 236 has asloped bottom plate 260 (shown in phantom in FIG. 9) to facilitate theremoval of solids which settle out of the contaminated cleaningsolution. The solids are periodically removed from the contaminatedsolution storage tank 236 via the solids outlet 246 which is providedwith a valve 262.

The fluid outlet 244 is provided with a valve 264 and is selectivelyconnectable to the portable wastewater apparatus 234. Similarly, thesecond fluid inlet 242 is selectively connectable to the wastewatertreatment apparatus 234. However, the second fluid inlet 242 is providedwith a three-way electric valve 266 which allows fluid to be selectivelypassed into the contaminated solution storage tank 236 or into thetreated solution storage tank 238 via a conduit 268 which provides fluidcommunication with the treated solution storage tank 238.

The contaminated solution storage tank 236 is further provided with acontrol panel 270 on one side of the contaminated solution storage tank236. The control panel 270 contains a switch 272 which is electricallyconnected to the three-way valve 266, an air hose connection 274 whichis connected to an air supply 276, and an electric outlet 278 which isconnected to a power supply 280. Further detail of the operation of thecontrol panel will be described hereinbelow.

The treated solution storage tank 238 includes a fluid inlet 282, afluid outlet 284, and a solids outlet 286. Treated cleaning solution ispassed into the treated solution storage tank 238 via conduit 268 whichinterconnects the three-way valve 266 and the fluid inlet 282 of thetreated solution storage tank 238. The fluid inlet 282 is provided witha valve 288.

As illustrated in FIG. 8, the fluid outlet 284 is connectable to theparts washer assembly 222 via a conduit 290 interconnecting thereservoir 226 and the fluid outlet 284 of the treated solution storagetank 238. The conduit 290 in FIG. 8 is shown to have a pump 292interposed therein for transferring the treated cleaning solution to thereservoir 226. Alternatively, a portable pump can be selectively coupledto the fluid outlet 284 and the fluid inlet of the reservoir 226 totransfer the treated cleaning solution in a manner to be discussed infurther detail hereinbelow.

In order that an operator can monitor the amount of cleaning solution inthe treated solution storage tank 238, the treated solution storage tank238 is provided with a liquid level sensing unit 294 which includes ashort probe 296 and a long probe 298, each electrically connected to alight 300 mounted on the top of the treated solution storage tank 238.The long probe 298 extends into the treated solution storage tank 238such that the long probe 298 extends a predetermined distance from thebottom of the treated solution storage tank 238. The short probe 296extends into the treated solution storage tank 238 a predetermineddistance such that the short probe 296 energizes the light 300 when thetreated cleaning solution rises to the level of the short probe 296. Thelight 300 serves to inform an operator that the treated solution storagetank 238 is filled.

Like the contaminated solution storage tank 236, the treated solutionstorage tank 238 has a sloped bottom plate 302 (shown in phantom in FIG.9) to facilitate the removal of solids which settle out of thecontaminated cleaning solution. The solids are periodically removed fromthe treated solution storage tank 238 via the solids outlet 286. Thesolids outlet 286 is provided with a valve 304 and preferably the solidsoutlet 286 of the treated solution storage tank 238 is connected to thesolids outlet 246 of the contaminated solution storage tank 236 with aconduit 306 such that solids can be removed from each tanksimultaneously.

To enable a portion of the cleaning solution present in the treatedsolution storage tank 238 to be used to wash the side walls of thereservoir 226 after the contaminated cleaning solution has beentransferred to the contaminated solution storage tank 236, a pressurewasher 308 is operably connected to the treated solution storage tank238 so that a portion of the cleaning solution in the treated solutionstorage tank 238 can be injected into the reservoir 226 at a sufficientpressure to flush or wash the reservoir 226. The cleaning solution isinjected into the reservoir 226 from the pressure washer 308 via a spraywand 309.

After several parts washing operations and periodic changes of thecleaning solution in the reservoir 226, a volume of contaminatedcleaning solution accumulates in the contaminated solution storage tank236. When a predetermined volume of contaminated cleaning solutionaccumulates in the contaminated solution storage tank 236, the portablewastewater treatment apparatus 234 is positioned in close proximity tothe contaminated and treated solution storage tanks 236, 238 so that thewastewater treatment apparatus 234 can be connected to the fluid outlet244 and the second fluid inlet 242 of the contaminated solution storagetank 236. The wastewater treatment apparatus 234 treats the contaminatedcleaning solution in a manner to remove the oils, particulate matter,and dissolved heavy metals from the cleaning solution and thereaftertransfers the treated cleaning solution back to the treated solutionstorage tank 238 for reuse in the parts washer assembly 222.

Referring now to FIGS. 10-12, the portable wastewater treatmentapparatus 234 is similar in construction to the treatment cell 18 or 20described above. As best shown in FIG. 10, the portable wastewatertreatment apparatus 234 includes a housing 310 having a fluid inlet 312with a pump 314 and a fluid outlet 316 with a pump 318. To permit thewastewater treatment apparatus 234 to be freely moved from one partswasher assembly to another, the housing 310 is mounted to a supportframe 320 which is supported on a plurality of wheels 322 (only twoshown) to form, in essence, a wastewater treatment cart. A handle 324 isfixed to the housing 310 to facilitate movement of the wastewatertreatment apparatus 234.

A cabinet 326 for containing a retractable air hose 328, a retractableelectric cord 330, an assortment of switches is mounted on one side ofthe housing 310. The air hose 328 is adapted to be connected to the airhose connection 274 provided on the contaminated solution storage tank236 so as to readily provide a source of compressed air to thewastewater treatment apparatus 234. Similarly, the electric cord 330 isadapted to be connected to the electric outlet 278 on the contaminatedsolution storage tank 236 to provide a source of power with which tooperate the various components of the wastewater treatment apparatus234.

As best illustrated in FIG. 11, the housing 310 has a bottom 331 anddefines an internal chamber 332. A baffle 334 is connected to thehousing 310 and supported within the internal chamber 332. The baffle334 cooperates with a portion of the housing 310 to define a mixing zone336. A baffle 338 is disposed in the internal chamber 332 near thebaffle 334 for defining a path for the wastewater to be passed from themixing zone 336.

A baffle 340 is disposed in the internal chamber 332 near one end of thehousing 310, opposite the end of the housing 310 forming the mixing zone336. The baffle 340 cooperates with a portion of the housing 310 todefine a discharge zone 342 in the internal chamber 332. A baffle 344 isdisposed in the internal chamber 332 and positioned near the baffle 340for defining a path through which the treated wastewater passes into thedischarge zone 342. The area in the internal chamber 332 between thebaffle 344 and the baffle 334 or, in other words, between the mixingzone 336 and the discharge zone 342 defines a quiescent zone 346.

The baffle 340 has an upper end 348 and a lower end 350. The lower end350 is secured to the bottom of the housing 310 and the upper end 348 ispositioned above the liquid level of the wastewater in the internalchamber 332 of the housing 310. An opening 352 is formed through thebaffle 340 and positioned near the upper end 348. The treated cleaningsolution passes through the opening 352 into the discharge zone 342.

As described above in reference to FIG. 5, an adjustable cover plate(not shown) can be positioned adjacent the baffle 340 to selectivelycontrol the amount of treated cleaning solution passed from thequiescent zone 346 into the discharge zone 342. The cover plate is sizedand positioned to cover and substantially close the opening 352.

The contaminated cleaning solution passes into the mixing zone 336 viathe fluid inlet 312. Prior to passing the contaminated cleaning solutioninto the mixing zone 336 of the housing 310, a chemical treating agentand compressed air provided by the air supply 276 (FIG. 9) areintroduced into the contaminated cleaning solution. The air hose 328 isretracted from the cabinet 326 and connected to the air hose connection274 on the contaminated solution storage tank 236. As shown in FIG. 10,the air hose 328 interconnects the air supply 276 and an air injectionline 354 which in turn is connected to the fluid inlet 312 via an airinjection fitting 356. The air injection line 354 is provided with acontrol valve 358 to permit the injection of air to be selectivelyterminated during certain phases of the treatment process. Thecompressed air is introduced into the contaminated cleaning solution inan amount sufficient so that large air bubbles are formed in thecontaminated cleaning solution in the mixing zone of the housing 310.

The chemical treating agent injected into the contaminated cleaningsolution promotes the aggregation of smaller particles into largerparticles so that contaminants are more readily settled to the bottom orfloated to the surface with the assistance of air bubbles. The chemicaltreating agent is injected into the contaminated cleaning solution viaan injection fitting 360 and a pump 362.

A spray nozzle 364 (FIG. 11) is provided above the liquid level in themixing zone 336. The spray nozzle 364 is connected to a water supplyline 366 which is connected to a water supply. Water can be supplied tothe spray nozzle 364 in any suitable manner; however, the spray nozzle364 is preferably interconnected to the fluid outlet 316, therebyallowing a portion of the treated cleaning solution to be passed to thespray nozzle 364 and sprayed into the contaminated cleaning solution inthe mixing zone 336.

The spray water is preferably aerated by injecting a portion of the airpassing through the air injection line 354 into the water supply line366 prior to the water being sprayed into the mixing zone 336 via thenozzle 364.

The contaminated cleaning solution in the mixing zone 336 is sprayedwith water from the nozzle 364. The nozzle 364 is positioned above theliquid level of the contaminated cleaning solution in the mixing zone336. The water is sprayed onto the surface of the contaminated cleaningsolution in the mixing zone 336 so that the sprayed water contacts thelarge air bubbles in the mixing zone 336 and substantially reduces thesize of the large air bubbles in the mixing zone 336.

The contaminated cleaning solution (which now contains a large number ofsmall bubbles) is passed from the mixing zone 336 into the quiescentzone 346 as indicated. In the quiescent zone 346 the contaminatedcleaning solution separates into an upper layer containing light sludgeor a sludge less dense than the cleaning solution, an intermediate layerconstituting a treated cleaning solution, and a lower layer containing aheavy sludge or a sludge more dense than the cleaning solution.

The heavy sludge is permitted to settle to the bottom of the housing 310into a heavy sludge area 368 (FIG. 11) formed in the internal chamber332 near the bottom of the housing 32. More particularly, the bottom 331of the housing 310 comprises a cone shaped member 370. The cone shapedmember 370 surrounds and defines the heavy sludge area 368.

In the quiescent zone 346, light sludge rises to the upper liquid levelof the contaminated cleaning solution forming and defining a lightsludge area 372 positioned near the top of the liquid level in thequiescent zone 346. The treated cleaning solution formed in thequiescent zone 346 between the heavy sludge area 368 and the lightsludge area 372 is passed from the quiescent zone 346 upwardly betweenthe baffles 44 and 48 and discharged through the opening 352 in thebaffle 340 into the discharge zone 342 as indicated. The treatedcleaning solution is passed from the discharge zone 342 through thefluid outlet 316 by the pump 318.

A discharge conduit 374 (FIGS. 11 and 12) is connected to the coneshaped member 370 and the opening through the discharge conduit 374 isin fluid communication with the heavy sludge area 368. The heavy sludgein the heavy sludge area 368 is passed through the discharge conduit 374and discharged from the heavy sludge area 368 during one aspect of theoperation as will be described below.

A valve 376 is interposed in the conduit 374. The valve 376 has anopened position and a closed position. In the opened position, the valve376 establishes fluid communication through the conduit 374 fordischarging the heavy sludge from the heavy sludge area 368 through theconduit 374 for transferring the heavy sludge to a disposal container aswill be described below. The valve 376 is a solenoid or electricallyoperated type of valve (normally closed) and includes a valve controller378 adapted to receive an electrical signal by way of a signal path 380in response to turning on a manual switch (not shown) located in thecabinet 326. The use of the manual switch allows the valve 376 to beopened for predetermined discharge times and at predetermined dischargeintervals for selectively controlling the discharge of the heavy sludgefrom the heavy sludge area 368.

Similar to the treatment cell 18 and 20 described above, the wastewatertreatment apparatus 234 includes a rake 382 (FIG. 11). The rake 382includes an elongated solid bar 384 having a rubber flap 386 attached toand extending a distance from the bottom of the bar 384. The rake 382operates in a similar manner as previously described with reference tothe rake 126, except that the rake 382 used with the portable wastewatertreatment apparatus 234 is operated via a manual switch (not shown)located in the cabinet 326 which allows an operator to selectivelycontrol the removal of the light sludge from the light sludge area 372.The housing 310 is provided with a removable lid 388 to enclose the rake382 and its components.

As shown in FIG. 12, a light sludge bin 390 is connected to one side ofthe housing 310 and an upper end of the light sludge bin 390 ispositioned near an opening 392 (shown in phantom in FIG. 12) in thehousing 310 which provides communication between the quiescent zone 346and the light sludge bin 390. The light sludge bin 390 has a cone shapedlower portion 394. A discharge conduit 396 (FIG. 12) is connected to alower end of the light sludge bin 390 and positioned so that the conduit396 is in fluid communication with the interior space (not shown) in thelight sludge bin 390.

A control solenoid type valve 398 (normally closed) is interposed in thedischarge conduit 396. The control valve 398 has a valve controller 400which is a adapted to receive an electrical signal via a signal path 402in response to turning on the switch (not shown) which is alsoelectrically connected to the valve 376.

The control valve 398 has an opened position and a closed position. Inresponse to receiving a an electrical signal in response to turning onthe switch, the valve controller 400 causes the control valve 398 toopen thereby establishing fluid communication through the dischargeconduit 396 and permitting light sludge in the light sludge bin 390 tobe discharged therefrom.

The portable wastewater treatment apparatus 234 shown herein isconstructed so that the discharge of heavy sludge from the heavy sludgearea 368 and light sludge from the light sludge bin 390 is controlled bya single manual switch. However, in operation one may find that heavysludge will build up quicker in the heavy sludge area 368 than in thelight sludge bin 390, and therefore, it may be desired to adapt thewastewater treatment apparatus 234 so that the discharge of the heavysludge and the discharge of the light sludge are individuallycontrollable.

The pumps 314, 318, the chemical treating agent pump 362 and the controlvalve 358 disposed in the air injection line 354 are electricallyconnected to a three-way switch 404 located on the cabinet 326.Employment of the three-way switch 404 allows an operator tosimultaneously activate the chemical injection pump 362, the pumps 314,318 so as to circulate cleaning solution through the housing 310, and toopen the control valve 358 so as to start the injection of air into thecontaminated cleaning solution. Further, the three-way switch 404permits an operator to selectively discontinue the injection of the airand the chemical treating agent while the pumps 314 and 318 continue topass fluid through the housing 310. The significance of this will beexplained in more detail below.

FIG. 13 illustrates a portable cart 406 having a base 408, a handle 410,and a plurality of wheels 412. The cart 406 is provided with a disposalcontainer 414, such as a 55 gallon drum, and a pump 416 having ansuction conduit 418 and a discharge conduit 420. In one mode of use, thepump 416 can be adapted to transfer contaminated cleaning solution fromthe reservoir 226 to the contaminated solution storage tank 236 andtreated cleaning solution from the treated solution storage tank 238 tothe reservoir 226 by connecting the conduit 418 to the appropriate inletor outlet and connecting the conduit 420 to the appropriate inlet oroutlet. Utilization of the pump 416 can reduce costs in that it reducesthe number of pumps used, particularly if several parts washerassemblies are being employed at one location. In another mode of use,the pump 416 is used to transfer solids from the reservoir 226, thecontaminated solution storage tank 236 and the treated solution storagetank 238, and the wastewater treatment apparatus 234 to the disposalcontainer 414.

OPERATION

In operation, when the cleaning solution in the reservoir 226 is spent,the contaminated cleaning solution in the reservoir 226 is passed fromthe reservoir 226 to the contaminated solution storage tank 236. Thecontaminated cleaning solution can be transferred to the contaminatedsolution storage tank 236, as illustrated in FIG. 8, via the pump 250interposed in the conduit 248, or by positioning and coupling thesuction conduit 418 to the fluid outlet of the reservoir 226 and thedischarge conduit 420 to the first fluid inlet 240 of the contaminatedsolution storage tank 236 such that the portable pump 416 is operablydisposed between the reservoir 226 and the contaminated solution storagetank 236 so as to be able to transfer fluid from the reservoir 226 tothe contaminated solution storage tank 236. After the contaminatedcleaning solution has been transferred from the reservoir 226, any solidresidues which have settled and remain in the bottom of the reservoir226 are withdrawn and transferred to the disposal container 414 via thepump 416 by connecting the suction conduit 418 to a solids outlet 422 ofthe reservoir 226 and positioning the free end of the discharge conduit420 in the disposal container 414.

After the solids have been removed from the reservoir 226, apredetermined volume of treated or pretreated cleaning solutioncontained in the treated solution storage tank 238 is injected into thereservoir 226 by activating the pressure washer 308. The pressurizedcleaning solution flushes the sidewalls of the reservoir 226 of anyresidue that may remain thereon. The cleaning solution used to flush thereservoir 226 is then transferred to the contaminated fluid storage tank236. It should be noted that the long probe 298 in the treated solutionstorage tank 238 can be electrically connected to the pressure washer308 such that the pressure washer 308 is de-energized when the liquidlevel in the treated solution storage tank 238 drops below the longprobe 298. Finally, the reservoir 226 is filled with a volume ofcleaning solution from the treated solution storage tank 238.

At this point, the parts washer assembly 222 is again ready for use. Theparts washer assembly 222 is run through several parts cleaning cyclesand solution changing cycles as described above until a predeterminedvolume of contaminated cleaning solution is accumulated in thecontaminated solution storage tank 236 and conversely the cleaningsolution in the treated solution storage tank 238 has been depleted. Thelight 258 on the liquid level sensing unit 252 of the contaminatedsolution storage tank 236 will energize and thereby signal to anoperator that the cleaning solution in the contaminated solution storagetank 236 is in need of treatment.

At that point, the portable wastewater treatment apparatus 234 ispositioned near the cleaning solution storage tank assembly 232 and aflexible conduit 424 is connected between the fluid outlet 244 of thecontaminated solution storage tank 236 and the fluid inlet 312 of thewastewater treatment apparatus 234 so as to provide fluid communicationtherebetween, and a flexible conduit 426 is connected between the fluidoutlet 316 of wastewater treatment apparatus 234 and the second fluidinlet 242 of the contaminated solution storage tank 236. In furtherpreparing for treating the contaminated cleaning solution, the air hose328 is pulled from the cabinet 326 and connected to the air hoseconnection 274 on the contaminated solution storage tank 236 and theelectric cord 330 is pulled from the cabinet 326 and connected toelectric outlet 278 on the contaminated solution storage tank 236.

To begin treating the contaminated cleaning solution, the three-wayswitch 404 in the cabinet 326 of the wastewater treatment apparatus 234is turned to simultaneously activate the pumps 314, 318, the injectionof compressed air, and the injection of the chemical treating agent. Thepump 314 pulls liquid from the contaminated solution storage tank 236and passes it through the fluid inlet 312 where the compressed air andchemical treating agent are injected into the contaminated cleaningsolution. The contaminated cleaning solution then passes into the mixingzone 336 where large air bubbles form in the cleaning solution and movetoward the surface. Water is sprayed onto the cleaning solution in themixing zone 336 so that the sprayed water contacts the large air bubblesin the mixing zone 336 and substantially reduces the size of the largeair bubbles in the mixing zone 336.

The cleaning solution passes from the mixing zone 336 into the quiescentzone 346 where it separates into an upper layer containing light sludge,an intermediate layer constituting a treated cleaning solution and alower layer containing a heavy sludge. The quiescent zone 346 ischaracterized by reduced turbulence so that suspended oils and solidsfloat to the surface with the assistance of air bubbles and treatmentchemicals to form a froth at the surface, while the denser solids whichsettle to the bottom remain at the bottom. A middle layer ofonce-treated cleaning solution containing a reduced amount of suspendedoils and solids is produced. The reduced turbulence in the quiescentzone 346 promotes the growth of the froth which is periodically skimmedwith the rake 382 into the light sludge bin 390.

The treated cleaning solution is passed from the quiescent zone 346through the opening 352 to the discharge zone 342. The treated cleaningsolution in the discharge zone 342 contains a reduced level ofcontaminants and, in some cases, will be suitable for reuse. However, inmany instances the cleaning solution may need to be treated severaltimes. In that instance, the three-way valve 266 disposed in the secondfluid inlet 242 of the contaminated solution storage tank 236 ispositioned such that the fluid outlet 316 of the wastewater treatmentapparatus 234 is in fluid communication with the contaminated solutionstorage tank 236, thus allowing the cleaning solution discharged fromthe discharge zone 342 of the housing 310 to pass back into thecontaminated solution storage tank 236 via pump 318 and thereafter becontinuously recirculated through the wastewater treatment apparatus 234for a predetermined amount of time.

When the cleaning solution is sufficiently free of oils, particularmatter and dissolved heavy materials, the three-way switch 404 is turnedto deactivate the injection of air and chemical treating agent, butmaintain the operation of the pumps 314 and 318. The three-way valve 266interposed in the second fluid inlet 242 of the contaminated solutionstorage tank 236 is then positioned with the switch 272 to provide fluidcommunication between the fluid outlet 316 of the wastewater treatmentapparatus 234 and the treated solution storage tank 238 via the conduit268, and thus allow the treated cleaning solution to be discharged intothe treated solution storage tank 238.

When the fluid level in the contaminated solution storage tank 236 fallsbelow the long probe 256, the pumps 314 and 318 are de-energized. Itwill be appreciated that the pumps 314 and 318 can be operably connectedto the liquid level sensing unit 252 such that the pumps 314, 318 arede-energized automatically when the fluid level in the contaminatedsolution storage tank falls below the long probe 256. Once thewastewater treatment apparatus 234 has been deactivated, the wastewatertreatment apparatus 234 is disconnected from the solution storage tankassembly 232.

When solids need to be removed from the heavy sludge area 368 and thelight sludge bin 390, the pump 416 on the cart 406 is operably connectedto conduit 374. The valves 376 and 398 are then opened with a switch(not shown) located in the cabinet 326 and the pump 416 is actuatedthereby transferring the solids from the heavy sludge area 368 and thelight sludge bin 390 to the disposal container 414.

In a similar manner, when solids need to be removed from thecontaminated solution storage tank 236 and the treated solution storagetank 238, the pump 416 on the cart 406 is operably connected to conduit306. The valves 262 and 304 are then manually opened and the pump 416 isactuated thereby transferring the solids from the contaminated solutionstorage tank 236 and the treated solution storage tank 238 to thedisposal container 414.

It will be appreciated by those skilled in the art that the contaminatedcleaning solution can be treated with the portable wastewater treatmentapparatus 234 by connecting the wastewater treatment apparatus 234directly to the reservoir 226 of the parts washer assembly 222, withoutemploying the cleaning solution storage tank assembly 232, andcontinuously circulating the contaminated cleaning solution between thewastewater treatment apparatus 232 and the reservoir 226 of the partswasher assembly 222 until the cleaning solution is sufficiently free ofoils, particular matter, and dissolved heavy materials. While thisprocedure will effectively treat contaminated cleaning solution, it doesresult in a longer downtime of the parts washer assembly as the partswasher assembly is taken out of operation as the cleaning solution isbeing treated.

The wastewater treatment assembly 220 described above provides severaladvantages. First, the wastewater treatment assembly 220 provides anapparatus for removing contaminants from wastewater to produce asolution suitable for recycle. Thus, manufacturing plants andremanufacturing plants which often employ numerous parts washerassemblies will decrease costs of waste disposal, including surchargesand fines connected with the disposal of contaminants, and costs ofwater and detergent consumption. Second, the fact that the wastewatertreatment apparatus 234 is portable enables a manufacturing plant toselectively treat the cleaning solution of several parts washerassemblies at the plant personnel's convenience without disruptingproduction. With use of the present invention, the only downtime of theparts washer assemblies is when cleaning solution is being transferredbetween parts washer assembly and the cleaning solution storage tankassembly. Otherwise, the parts washer assembly can be operated in anormal manner, including the period during which contaminated cleaningsolution is being treated.

Changes may be made in the construction and the operation of the variouscomponents, elements and assemblies described herein and changes may bemade in the steps or the sequence of steps of the methods describedherein without departing from the spirit and scope of the invention asdefined in the following claims.

What is claimed:
 1. A method for recycling a contaminated aqueoussurfactant solution of a parts washer assembly, comprising the stepsof:(a) passing the contaminated aqueous surfactant solution from theparts washer assembly into a mixing zone in a housing; (b) introducingair into the contaminated aqueous surfactant solution prior to thecontaminated aqueous surfactant solution being introduced into themixing zone in an amount sufficient so that large air bubbles are formedin the contaminated aqueous surfactant solution in the mixing zone; (c)introducing water into the mixing zone so that the water contacts thelarge air bubbles formed in the contaminated aqueous surfactant solutionin the mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (d) passing the contaminated aqueous surfactant solution from themixing zone into a quiescent zone in the housing where the contaminatedaqueous surfactant solution is separated into an upper layer containinglight sludge, an intermediate layer constituting a treated aqueoussurfactant solution and a lower layer containing a heavy sludge; (e)passing the treated aqueous surfactant solution from the quiescent zoneinto a discharge zone in the housing; and (f) passing the treatedaqueous surfactant solution from the discharge zone to the parts washerassembly.
 2. The method of claim 1 further comprising the stepsof:repeating steps (a)-(f) until the treated aqueous surfactant solutionis substantially free of oils, particulate matter and dissolved heavymetals.
 3. The method of claim 1 further comprising the stepof:introducing a chemical treating agent into the aqueous surfactantsolution prior to the aqueous surfactant solution being introduced intothe mixing zone.
 4. The method of claim 1 further comprising the stepof:passing the heavy sludge from the housing to a disposal container. 5.The method of claim 1 further comprising the step of:skimming the lightsludge from the housing; and passing the light sludge from the housingto a disposal container.
 6. The method of claim 1 further comprising thestep of:withdrawing solids remaining in the parts washer assembly fromthe parts washer assembly and passing the solids to a disposalcontainer.
 7. A method for recycling a contaminated aqueous surfactantsolution of a parts washer assembly, comprising the steps of:(a) passingthe contaminated aqueous surfactant solution from the parts washerassembly to a contaminated solution storage tank; (b) accumulating avolume of the contaminated aqueous surfactant solution in thecontaminated solution storage tank; (c) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into a mixing zone in a housing; (d) introducing air intothe contaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone in anamount sufficient so that large air bubbles are formed in thecontaminated aqueous surfactant solution in the mixing zone; (e)introducing water into the mixing zone so that the water contacts thelarge air bubbles formed in the contaminated aqueous surfactant solutionin the mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (f) passing the contaminated aqueous surfactant solution from themixing zone into a quiescent zone in the housing where the contaminatedaqueous surfactant solution is separated into an upper layer containinglight sludge, an intermediate layer constituting a treated aqueoussurfactant solution and a lower layer containing a heavy sludge; (g)passing the treated aqueous surfactant solution from the quiescent zoneinto a discharge zone in the housing; and (h) passing the treatedaqueous surfactant solution from the discharge zone to a treated aqueoussurfactant solution storage tank.
 8. The method of claim 7 furthercomprising the steps of:prior to step (h), passing the treated aqueoussurfactant solution from the discharge zone of the housing to thecontaminated solution storage tank; repeating steps (c)-(g) and (i)until the treated aqueous surfactant is substantially free of oils,particulate matter and dissolved heavy metals; and passing the treatedaqueous surfactant solution to the treated solution storage tank.
 9. Themethod of claim 7 further comprising the step of:introducing a chemicaltreating agent into the aqueous surfactant solution prior to the aqueoussurfactant solution being introduced into the mixing zone.
 10. Themethod of claim 7 further comprising the step of:passing the heavysludge from the housing to a disposal container.
 11. The method of claim7 further comprising the step of:skimming the light sludge from thehousing; and passing the light sludge from the housing to a disposalcontainer.
 12. The method of claim 7 further comprising the stepof:withdrawing solids remaining in the contaminated solution storagetank from the contaminated solution storage tank and passing the solidsto a disposal container.
 13. The method of claim 7 further comprisingthe step of:withdrawing solids remaining in the treated solution storagetank from the treated solution storage tank and passing the solids to adisposal container.
 14. The method of claim 7 further comprising thestep of:withdrawing solids remaining in the contaminated solutionstorage tanks and the treated solution storage tanks from thecontaminated solution storage tanks and the treated solution storagetanks and passing the solids to a disposal container.
 15. The method ofclaim 7 further comprising the step of:withdrawing solids remaining inthe parts washer assembly from the parts washer assembly and passing thesolids to a disposal container.
 16. The method of claim 7 furthercomprising the steps of:monitoring the amount of the aqueous surfactantsolution accumulated in the contaminated solution storage tank; andselectively passing the accumulated aqueous solution from thecontaminated solution storage tank to the housing when a predeterminedamount of aqueous surfactant solution has accumulated in thecontaminated solution storage tank.
 17. The method of claim 7 furthercomprising the steps of:injecting a volume of treated aqueous surfactantsolution from the treated solution storage tank into the parts washerassembly at a sufficient pressure to flush the parts washer assembly;passing the flushing aqueous surfactant solution from the parts washerassembly to the contaminated solution storage tank; and passing a volumeof the treated aqueous surfactant solution suitable for operating theparts washer assembly from the treated solution storage tank to theparts washer assembly.
 18. The method of claim 7 further comprising thesteps of:operating the parts washer assembly; and concurrently passingthe accumulated aqueous surfactant solution from the contaminatedsolution storage tank into the mixing zone such that the parts washerassembly is operating while the aqueous surfactant solution is beingpassed through the housing.
 19. A method for recycling a contaminatedaqueous surfactant solution of a parts washer assembly, comprising thesteps of:(a) passing the contaminated aqueous surfactant solution fromthe parts washer assembly to a contaminated solution storage tank; (b)accumulating a volume of the contaminated aqueous surfactant solution inthe contaminated solution storage tank; (c) selectively connecting aportable housing having a fluid inlet and a fluid outlet to thecontaminated solution storage tank and a treated solution storage tanksuch that the fluid inlet of the housing is in fluid communication withthe contaminated solution storage tank and the fluid outlet of thehousing is in fluid communication with the treated solution storagetank, the housing having a mixing zone, a quiescent zone and a dischargezone; (d) passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing via the fluid inlet; (e) introducing air into thecontaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone in anamount sufficient so that large air bubbles are formed in thecontaminated aqueous surfactant solution in the mixing zone; (f)introducing water into the mixing zone so that the water contacts thelarge air bubbles formed in the contaminated aqueous surfactant solutionin the mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (g) passing the contaminated aqueous surfactant solution from themixing zone into the quiescent zone where the contaminated aqueoussurfactant solution is separated into an upper layer containing lightsludge, an intermediate layer constituting a treated aqueous surfactantsolution and a lower layer containing a heavy sludge; (h) passing thetreated aqueous surfactant solution from the quiescent zone into thedischarge zone; and (i) passing the treated aqueous surfactant solutionfrom the discharge zone to the treated solution storage tank.
 20. Themethod of claim 19 further comprising the steps of:(j) connecting thedischarge zone of the housing to the contaminated solution storage tanksuch that the fluid outlet of the housing is in fluid communication withthe contaminated solution storage tank; (k) prior to step (i), passingthe treated aqueous surfactant solution from the discharge zone to thecontaminated solution storage tank; (l) repeating steps (c)-(h) and (k)until the treated aqueous surfactant solution is substantially free ofoils, particulate matter and dissolved heavy metals; and (m) passing thetreated aqueous surfactant solution to the treated solution storagetank.
 21. The method of claim 19 further comprising the stepof:introducing a chemical treating agent into the aqueous surfactantsolution prior to the aqueous surfactant solution being introduced intothe mixing zone.
 22. The method of claim 19 further comprising the stepof:selectively passing the heavy sludge from the housing to a disposalcontainer.
 23. The method of claim 19 further comprising the stepof:skimming the light sludge from the quiescent zone; and selectivelypassing the light sludge to a disposal container.
 24. The method ofclaim 19 further comprising the step of:selectively passing solidsdisposed in the contaminated solution storage tank from the contaminatedsolution storage tank to a disposal container.
 25. The method of claim19 further comprising the step of:selectively passing solids disposed inthe treated solution storage tank from the treated solution storage tankto a disposal container.
 26. The method of claim 19 further comprisingthe step of:selectively passing solids disposed in the contaminatedsolution and treated solution storage tanks from the contaminatedsolution and treated solution storage tanks to a disposal container. 27.The method of claim 19 further comprising the step of:selectivelypassing solids disposed in the parts washer assembly from the partswasher assembly to a disposal container.
 28. The method of claim 19further comprising the steps of:monitoring the amount of the aqueoussurfactant solution accumulated in the contaminated solution storagetank; and selectively passing the accumulated aqueous solution from thecontaminated solution storage tank to the housing when a predeterminedamount of aqueous surfactant solution has accumulated in thecontaminated solution storage tank.
 29. The method of claim 19 furthercomprising the steps of:injecting a volume of treated aqueous surfactantsolution from the treated solution storage tank into the parts washerassembly at a sufficient pressure to flush the parts washer assembly;passing the flushing aqueous surfactant solution from the parts washerassembly to the contaminated solution storage tank; and passing a volumeof the treated aqueous surfactant solution suitable for operating theparts washer assembly from the treated solution storage tank to theparts washer assembly.
 30. The method of claim 19 further comprising thesteps of:operating the parts washer assembly; and concurrently passingthe accumulated aqueous surfactant solution from the contaminatedsolution storage tank into the mixing zone such that the parts washerassembly is operating while the aqueous surfactant solution is beingpassed through.
 31. A method for recycling contaminated aqueoussurfactant solution from a plurality of parts washer assemblies,comprising the steps of:(a) providing each of the parts washerassemblies with a contaminated solution storage tank and a treatedsolution storage tank wherein the contaminated solution storage tank andthe treated solution storage tank are in fluid communication with theparts washer assembly; (b) selectively passing the contaminated aqueoussurfactant solution from each of the parts washer assemblies to thecontaminated solution storage tank in fluid communication therewith; (c)accumulating a volume of the contaminated aqueous surfactant solution inthe contaminated solution storage tanks; (d) selectively connecting aportable housing having a fluid inlet and a fluid outlet to one of thecontaminated solution storage tanks and the adjacent treated solutionstorage tank such that the fluid inlet of the housing is in fluidcommunication with the contaminated solution storage tank and the fluidoutlet of the housing is in fluid communication with the treatedsolution storage tank, the housing having a mixing zone, a quiescentzone and a discharge zone; (e) passing the accumulated contaminatedaqueous surfactant solution from the contaminated solution storage tankinto the mixing zone of the housing via the fluid inlet; (f) introducingair into the contaminated aqueous surfactant solution prior to thecontaminated aqueous surfactant solution being introduced into themixing zone in an amount sufficient so that large air bubbles are formedin the contaminated aqueous surfactant solution in the mixing zone; (g)introducing water into the mixing zone so that the water contacts thelarge air bubbles formed in the contaminated aqueous surfactant solutionin the mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (h) passing the contaminated aqueous surfactant solution from themixing zone into the quiescent zone where the contaminated aqueoussurfactant solution is separated into an upper layer containing lightsludge, an intermediate layer constituting a treated aqueous surfactantsolution and a lower layer containing a heavy sludge; (i) passing thetreated aqueous surfactant solution from the quiescent zone into thedischarge zone; (j) passing the treated aqueous surfactant solution fromthe discharge zone to the treated solution storage tank; and (k)repeating steps (d)-(j) for the contaminated solution storage tanks ofeach parts washer assembly.
 32. The method of claim 31 furthercomprising the steps of:(l) connecting the discharge zone of the housingto the contaminated solution storage tank such that the fluid outlet ofthe housing is in fluid communication with the contaminated solutionstorage tank; (m) prior to step (j), passing the treated aqueoussurfactant solution from the discharge zone to the contaminated solutionstorage tank; (n) repeating steps (d)-(i) and (m) until the treatedaqueous surfactant solution is substantially free of oils, particulatematter and dissolved heavy metals; and (o) passing the treated aqueoussurfactant solution to the treated solution storage tank.
 33. The methodof claim 31 further comprising the step of:introducing a chemicaltreating agent into the aqueous surfactant solution prior to the aqueoussurfactant solution being introduced into the mixing zone.
 34. Themethod of claim 31 further comprising the step of:selectively passingthe heavy sludge from the housing to a disposal container.
 35. Themethod of claim 31 further comprising the steps of:skimming the lightsludge from the quiescent zone; and selectively passing the light sludgeto a disposal container.
 36. The method of claim 31 further comprisingthe step of:selectively passing solids disposed in the contaminatedsolution storage tank from the contaminated solution storage tank to adisposal container.
 37. The method of claim 31 further comprising thestep of:selectively passing solids disposed in the treated solutionstorage tank from the treated solution storage tank to a disposalcontainer.
 38. The method of claim 31 further comprising the stepof:selectively passing solids disposed in the contaminated solution andtreated solution storage tanks from the contaminated solution andtreated solution storage tanks to a disposal container.
 39. The methodof claim 31 further comprising the step of:selectively passing solidsdisposed in the parts washer assemblies from the parts washer assembliesto a disposal container.
 40. The method of claim 31 further comprisingthe steps of:monitoring the amount of the aqueous surfactant solutionaccumulated in the contaminated solution storage tank; and selectivelypassing the accumulated aqueous solution from the contaminated solutionstorage tank to the housing when a predetermined amount of aqueoussurfactant solution has accumulated in the contaminated solution storagetank.
 41. The method of claim 31 further comprising the stepsof:injecting a volume of treated aqueous surfactant solution from thetreated solution storage tank into the parts washer assembly at asufficient pressure to flush the parts washer assembly; passing theflushing aqueous surfactant solution from the parts washer assembly tothe contaminated solution storage tank; and passing a volume of thetreated aqueous surfactant solution suitable for operating the partswasher assembly from the treated solution storage tank to the partswasher assembly.
 42. The method of claim 31 further comprising the stepsof:operating the parts washer assembly; and concurrently passing theaccumulated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone such that the parts washer assembly isoperating while the aqueous surfactant solution is being passed through.43. The method of claim 1 further comprising the steps of:prior to step(f), recovering the treated aqueous surfactant solution from thedischarge zone of the housing; and repeating steps (b)-(e) until thetreated aqueous surfactant solution is substantially free of oils,particulate matter and dissolved heavy metals.
 44. The method of claim43 further comprising the step of:introducing a chemical treating agentinto the contaminated aqueous surfactant solution prior to the aqueoussurfactant solution being introduced into the mixing zone.
 45. Themethod of claim 43 further comprising the step of:passing the heavysludge from the housing to a disposal container.
 46. The method of claim43 further comprising the step of:skimming the light sludge from thehousing; and passing the light sludge from the housing to a disposalcontainer.
 47. The method of claim 43 further comprising the stepof:withdrawing solids remaining in the parts washer assembly from theparts washer assembly and passing the solids to a disposal container.48. A method for recycling a contaminated aqueous surfactant solution ofan apparatus comprising the steps of:(a) passing the contaminatedaqueous surfactant solution from the apparatus to a contaminatedsolution storage tank; (b) accumulating a volume of the contaminatedaqueous surfactant solution in the contaminated solution storage tank;(c) passing the accumulated contaminated aqueous surfactant solutionfrom the contaminated solution storage tank into a mixing zone in ahousing; (d) introducing air into the contaminated aqueous surfactantsolution prior to the contaminated aqueous surfactant solution beingintroduced into the mixing zone in an amount sufficient so that largeair bubbles are formed in the contaminated aqueous surfactant solutionin the mixing zone; (e) introducing water into the mixing zone so thatthe water contacts the large air bubbles formed in the contaminatedaqueous surfactant solution in the mixing zone and substantially reducesthe size of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (f) passing the contaminated aqueoussurfactant solution from the mixing zone into a quiescent zone in thehousing where the contaminated aqueous surfactant solution is separatedinto an upper layer containing light sludge, an intermediate layerconstituting a treated aqueous surfactant solution and a lower layercontaining a heavy sludge; (g) passing the treated aqueous surfactantsolution from the quiescent zone into a discharge zone in the housing;and (h) passing the treated aqueous surfactant solution from thedischarge zone to a treated aqueous surfactant solution storage tank.49. The method of claim 48 further comprising the steps of:prior to step(h), passing the treated aqueous surfactant solution from the dischargezone of the housing to the contaminated solution storage tank; repeatingsteps (c)-(g) and (i) until the treated aqueous surfactant issubstantially free of oils, particulate matter and dissolved heavymetals; and passing the treated aqueous surfactant solution to thetreated solution storage tank.
 50. The method of claim 48 furthercomprising the step of:introducing a chemical treating agent into thecontaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone. 51.The method of claim 48 further comprising the step of:passing the heavysludge from the housing to a disposal container.
 52. The method of claim48 further comprising the step of:skimming the light sludge from thehousing; and passing the light sludge from the housing to a disposalcontainer.
 53. The method of claim 48 further comprising the stepof:withdrawing solids remaining in the contaminated solution storagetank from the contaminated solution storage tank and passing the solidsto a disposal container.
 54. The method of claim 48 further comprisingthe step of:withdrawing solids remaining in the treated solution storagetank from the treated solution storage tank and passing the solids to adisposal container.
 55. The method of claim 48 further comprising thestep of:withdrawing solids remaining in the contaminated solutionstorage tanks and the treated solution storage tanks from thecontaminated solution storage tanks and the treated solution storagetanks and passing the solids to a disposal container.
 56. The method ofclaim 48 further comprising the step of:withdrawing solids remaining inthe apparatus from the apparatus and passing the solids to a disposalcontainer.
 57. The method of claim 48 further comprising the stepsof:monitoring the amount of the contaminated aqueous surfactant solutionaccumulated in the contaminated solution storage tank; and selectivelypassing the accumulated contaminated aqueous surfactant solution fromthe contaminated solution storage tank to the housing when apredetermined amount of contaminated aqueous surfactant solution hasaccumulated in the contaminated solution storage tank.
 58. The method ofclaim 48 further comprising the steps of:injecting a volume of treatedaqueous surfactant solution from the treated solution storage tank intothe apparatus at a sufficient pressure to flush the apparatus; passingthe flushing aqueous surfactant solution from the apparatus to thecontaminated solution storage tank; and passing a volume of the treatedaqueous surfactant solution suitable for operating the apparatus fromthe treated solution storage tank to the apparatus.
 59. The method ofclaim 48 further comprising the steps of:operating the apparatus; andconcurrently passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing such that the apparatus is operating while thecontaminated aqueous surfactant solution is being passed through thehousing.
 60. A method for recycling a contaminated aqueous surfactantsolution of an apparatus comprising the steps of:(a) passing thecontaminated aqueous surfactant solution from the apparatus to acontaminated solution storage tank; (b) accumulating a volume of thecontaminated aqueous surfactant solution in the contaminated solutionstorage tank; (c) selectively connecting a portable housing having afluid inlet and a fluid outlet to the contaminated solution storage tankand a treated solution storage tank such that the fluid inlet of thehousing is in fluid communication with the contaminated solution storagetank and the fluid outlet of the housing is in fluid communication withthe treated solution storage tank, the housing having a mixing zone, aquiescent zone and a discharge zone; (d) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing via the fluid inlet;(e) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone in an amount sufficient so that large air bubblesare formed in the contaminated aqueous surfactant solution in the mixingzone; (f) introducing water into the mixing zone so that the watercontacts the large air bubbles formed in the contaminated aqueoussurfactant solution in the mixing zone and substantially reduces thesize of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (g) passing the contaminated aqueoussurfactant solution from the mixing zone into the quiescent zone wherethe contaminated aqueous surfactant solution is separated into an upperlayer containing light sludge, an intermediate layer constituting atreated aqueous surfactant solution and a lower layer containing a heavysludge; (h) passing the treated aqueous surfactant solution from thequiescent zone into the discharge zone; and (i) passing the treatedaqueous surfactant solution from the discharge zone to the treatedsolution storage tank.
 61. The method of claim 60 further comprising thesteps of:(j) connecting the discharge zone of the housing to thecontaminated solution storage tank such that the fluid outlet of thehousing is in fluid communication with the contaminated solution storagetank; (k) prior to step (i), passing the treated aqueous surfactantsolution from the discharge zone to the contaminated solution storagetank; (l) repeating steps (c)-(h) and (k) until the treated aqueoussurfactant solution is substantially free of oils, particulate matterand dissolved heavy metals; and (m) passing the treated aqueoussurfactant solution to the treated solution storage tank.
 62. The methodof claim 60 further comprising the step of:introducing a chemicaltreating agent into the contaminated aqueous surfactant solution priorto the contaminated aqueous surfactant solution being introduced intothe mixing zone.
 63. The method of claim 60 further comprising the stepof:selectively passing the heavy sludge from the housing to a disposalcontainer.
 64. The method of claim 60 further comprising the stepof:skimming the light sludge from the quiescent zone; and selectivelypassing the light sludge to a disposal container.
 65. The method ofclaim 60 further comprising the step of:selectively passing solidsdisposed in the contaminated solution storage tank from the contaminatedsolution storage tank to a disposal container.
 66. The method of claim60 further comprising the step of:selectively passing solids disposed inthe treated solution storage tank from the treated solution storage tankto a disposal container.
 67. The method of claim 60 further comprisingthe step of:selectively passing solids disposed in the contaminatedsolution and treated solution storage tanks from the contaminatedsolution and treated solution storage tanks to a disposal container. 68.The method of claim 60 further comprising the step of:selectivelypassing solids disposed in the apparatus from the apparatus to adisposal container.
 69. The method of claim 60 further comprising thesteps of:monitoring the amount of the contaminated aqueous surfactantsolution accumulated in the contaminated solution storage tank; andselectively passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank to the housing whena predetermined amount of contaminated aqueous surfactant solution hasaccumulated in the contaminated solution storage tank.
 70. The method ofclaim 60 further comprising the steps of:injecting a volume of treatedaqueous surfactant solution from the treated solution storage tank intothe apparatus at a sufficient pressure to flush the apparatus; passingthe flushing aqueous surfactant solution from the apparatus to thecontaminated solution storage tank; and passing a volume of the treatedaqueous surfactant solution suitable for operating the apparatus fromthe treated solution storage tank to the apparatus.
 71. The method ofclaim 60 further comprising the steps of:operating the apparatus; andconcurrently passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing such that the apparatus is operating while thecontaminated aqueous surfactant solution is being passed through.
 72. Amethod for recycling contaminated aqueous surfactant solution from aplurality of apparatus comprising the steps of:(a) providing each of theapparatus with a contaminated solution storage tank and a treatedsolution storage tank wherein the contaminated solution storage tank andthe treated solution storage tank are in fluid communication with theapparatus; (b) selectively passing the contaminated aqueous surfactantsolution from each of the apparatus to the contaminated solution storagetank in fluid communication therewith; (c) accumulating a volume of thecontaminated aqueous surfactant solution in the contaminated solutionstorage tanks; (d) selectively connecting a portable housing having afluid inlet and a fluid outlet to one of the contaminated solutionstorage tanks and the adjacent treated solution storage tank such thatthe fluid inlet of the housing is in fluid communication with thecontaminated solution storage tank and the fluid outlet of the housingis in fluid communication with the treated solution storage tank, thehousing having a mixing zone, a quiescent zone and a discharge zone; (e)passing the accumulated contaminated aqueous surfactant solution fromthe contaminated solution storage tank into the mixing zone of thehousing via the fluid inlet; (f) introducing air into the contaminatedaqueous surfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone in an amount sufficientso that large air bubbles are formed in the contaminated aqueoussurfactant solution in the mixing zone; (g) introducing water into themixing zone so that the water contacts the large air bubbles formed inthe contaminated aqueous surfactant solution in the mixing zone andsubstantially reduces the size of the large air bubbles in thecontaminated aqueous surfactant solution in the mixing zone; (h) passingthe contaminated aqueous surfactant solution from the mixing zone intothe quiescent zone where the contaminated aqueous surfactant solution isseparated into an upper layer containing light sludge, an intermediatelayer constituting a treated aqueous surfactant solution and a lowerlayer containing a heavy sludge; (i) passing the treated aqueoussurfactant solution from the quiescent zone into the discharge zone; (j)passing the treated aqueous surfactant solution from the discharge zoneto the treated solution storage tank; and (k) repeating steps (d)-(j)for the contaminated solution storage tanks of each apparatus.
 73. Themethod of claim 72 further comprising the steps of:(l) connecting thedischarge zone of the housing to the contaminated solution storage tanksuch that the fluid outlet of the housing is in fluid communication withthe contaminated solution storage tank; (m) prior to step (j), passingthe treated aqueous surfactant solution from the discharge zone to thecontaminated solution storage tank; (n) repeating steps (d)-(i) and (m)until the treated aqueous surfactant solution is substantially free ofoils, particulate matter and dissolved heavy metals; and (o) passing thetreated aqueous surfactant solution to the treated solution storagetank.
 74. The method of claim 72 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone.
 75. The method of claim72 further comprising the step of:selectively passing the heavy sludgefrom the housing to a disposal container.
 76. The method of claim 72further comprising the steps of:skimming the light sludge from thequiescent zone; and selectively passing the light sludge to a disposalcontainer.
 77. The method of claim 72 further comprising the stepof:selectively passing solids disposed in the contaminated solutionstorage tank from the contaminated solution storage tank to a disposalcontainer.
 78. The method of claim 72 further comprising the stepof:selectively passing solids disposed in the treated solution storagetank from the treated solution storage tank to a disposal container. 79.The method of claim 72 further comprising the step of:selectivelypassing solids disposed in the contaminated solution and treatedsolution storage tanks from the contaminated solution and treatedsolution storage tanks to a disposal container.
 80. The method of claim72 further comprising the step of:selectively passing solids disposed inthe apparatus from the apparatus to a disposal container.
 81. The methodof claim 72 further comprising the steps of:monitoring the amount of thecontaminated aqueous surfactant solution accumulated in the contaminatedsolution storage tank; and selectively passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank to the housing when a predetermined amount of contaminatedaqueous surfactant solution has accumulated in the contaminated solutionstorage tank.
 82. The method of claim 72 further comprising the stepsof:injecting a volume of treated aqueous surfactant solution from thetreated solution storage tank into the apparatus at a sufficientpressure to flush the apparatus; passing the flushing aqueous surfactantsolution from the apparatus to the contaminated solution storage tank;and passing a volume of the treated aqueous surfactant solution suitablefor operating the apparatus from the treated solution storage tank tothe apparatus.
 83. The method of claim 72 further comprising the stepsof:operating the apparatus; and concurrently passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing such that the apparatusis operating while the aqueous surfactant solution is being passedthrough.
 84. A method for recycling a contaminated aqueous surfactantsolution of an apparatus comprising the steps of:(a) passing thecontaminated aqueous surfactant solution from the apparatus into amixing zone in a housing; (b) introducing air into the contaminatedaqueous surfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone in an amount sufficientso that large air bubbles are formed in the contaminated aqueoussurfactant solution in the mixing zone; (c) introducing water into themixing zone so that the water contacts the large air bubbles formed inthe contaminated aqueous surfactant solution in the mixing zone andsubstantially reduces the size of the large air bubbles in thecontaminated aqueous surfactant solution in the mixing zone; (d) passingthe contaminated aqueous surfactant solution from the mixing zone into aquiescent zone in the housing where the contaminated aqueous surfactantsolution is separated into an upper layer containing light sludge, anintermediate layer constituting a treated aqueous surfactant solutionand a lower layer containing a heavy sludge; (e) passing the treatedaqueous surfactant solution from the quiescent zone into a dischargezone in the housing; and (f) passing the treated aqueous surfactantsolution from the discharge zone to the apparatus.
 85. The method ofclaim 84 further comprising the steps of:repeating steps (a)-(f) untilthe treated aqueous surfactant solution is substantially free of oils,particulate matter and dissolved heavy metals.
 86. The method of claim84 further comprising the step of:introducing a chemical treating agentinto the contaminated aqueous surfactant solution prior to thecontaminated aqueous surfactant solution being introduced into themixing zone.
 87. The method of claim 84 further comprising the stepof:passing the heavy sludge from the housing to a disposal container.88. The method of claim 84 further comprising the step of:skimming thelight sludge from the housing; and passing the light sludge from thehousing to a disposal container.
 89. The method of claim 84 furthercomprising the step of:withdrawing solids remaining in the apparatusfrom the apparatus and passing the solids to a disposal container. 90.The method of claim 84 further comprising the step of:prior to step (f),recovering the treated aqueous surfactant solution from the dischargezone of the housing and repeating steps (b)-(e) until the treatedaqueous surfactant solution is substantially free of oils, particulatematter and dissolved heavy metals.
 91. The method of claim 90 furthercomprising the step of:introducing a chemical treating agent into thecontaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone. 92.The method of claim 90 further comprising the step of:passing the heavysludge from the housing to a disposal container.
 93. The method of claim90 further comprising the step of:skimming the light sludge from thehousing; and passing the light sludge from the housing to a disposalcontainer.
 94. The method of claim 90 further comprising the stepof:withdrawing solids remaining in the apparatus from the apparatus andpassing the solids to a disposal container.
 95. A method for recycling acontaminated aqueous surfactant solution of a parts washer assembly,comprising the steps of:(a) passing the contaminated aqueous surfactantsolution from the parts washer assembly into a mixing zone in a housing;(b) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone in an amount sufficient so that large air bubblesare formed in the contaminated aqueous surfactant solution in the mixingzone; (c) spraying water onto the contaminated aqueous surfactantsolution in the mixing zone so that the sprayed water contacts the largeair bubbles formed in the contaminated aqueous surfactant solution inthe mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (d) passing the contaminated aqueous surfactant solution from themixing zone into a quiescent zone in the housing where the contaminatedaqueous surfactant solution is separated into an upper layer containinglight sludge, an intermediate layer constituting a treated aqueoussurfactant solution and a lower layer containing a heavy sludge; (e)passing the treated aqueous surfactant solution from the quiescent zoneinto a discharge zone in the housing; and (f) passing the treatedaqueous surfactant solution from the discharge zone to a treated aqueoussurfactant solution storage tank.
 96. The method of claim 95 furthercomprising the step of:prior to step (f), recovering the treated aqueoussurfactant solution from the discharge zone in the housing and repeatingsteps (b)-(e) until the treated aqueous surfactant solution issubstantially free of oils, particulate matter and dissolved heavymetals.
 97. The method of claim 95 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the aqueous surfactant solution beingintroduced into the mixing zone.
 98. The method of claim 95 furthercomprising the step of:passing the heavy sludge from the housing to adisposal container.
 99. The method of claim 95 further comprising thestep of:skimming the light sludge from the housing; and passing thelight sludge from the housing to a disposal container.
 100. The methodof claim 95 further comprising the step of:withdrawing solids remainingin the treated solution storage tank from the treated solution storagetank and passing the solids to a disposal container.
 101. The method ofclaim 95 further comprising the step of:withdrawing solids remaining inthe parts washer assembly from the parts washer assembly and passing thesolids to a disposal container.
 102. The method of claim 95 furthercomprising the steps of:injecting a volume of treated aqueous surfactantsolution from the treated solution storage tank into the parts washerassembly at a sufficient pressure to flush the parts washer assembly;removing the flushing aqueous surfactant solution from the parts washerassembly for passage into the mixing zone in the housing; and passing avolume of the treated aqueous surfactant solution suitable for operatingthe parts washer assembly from the treated solution storage tank to theparts washer assembly.
 103. The method of claim 95 further comprisingthe steps of:operating the parts washer assembly; and concurrentlypassing the contaminated aqueous surfactant solution from the partswasher assembly into the mixing zone of the housing and treated aqueoussurfactant solution from the treated solution storage tank such that theparts washer assembly is operating while the contaminated aqueoussurfactant solution is being passed through the housing.
 104. A methodfor recycling a contaminated aqueous surfactant solution of a partswasher assembly, comprising the steps of:(a) passing the contaminatedaqueous surfactant solution from the parts washer assembly into a mixingzone in a housing; (b) introducing air into the contaminated aqueoussurfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone in an amount sufficientso that large air bubbles are formed in the contaminated aqueoussurfactant solution in the mixing zone; (c) introducing water into themixing zone so that the water contacts the large air bubbles formed inthe contaminated aqueous surfactant solution in the mixing zone andsubstantially reduces the size of the large air bubbles in thecontaminated aqueous surfactant solution in the mixing zone; (d) passingthe contaminated aqueous surfactant solution from the mixing zone into aquiescent zone in the housing where the contaminated aqueous surfactantsolution is separated into an upper layer containing light sludge, anintermediate layer constituting a treated aqueous surfactant solutionand a lower layer containing a heavy sludge; (e) passing the treatedaqueous surfactant solution from the quiescent zone into a dischargezone in the housing; and (f) passing the treated aqueous surfactantsolution from the discharge zone to a treated aqueous surfactantsolution storage tank.
 105. The method of claim 104 further comprisingthe step of:prior to step (f), recovering the treated aqueous surfactantsolution from the discharge zone in the housing and repeating steps(b)-(e) until the treated aqueous surfactant solution is substantiallyfree of oils, particulate matter and dissolved heavy metals.
 106. Themethod of claim 104 further comprising the step of:introducing achemical treating agent into the contaminated aqueous surfactantsolution prior to the aqueous surfactant solution being introduced intothe mixing zone.
 107. The method of claim 104 further comprising thestep of:passing the heavy sludge from the housing to a disposalcontainer.
 108. The method of claim 104 further comprising the stepof:skimming the light sludge from the housing; and passing the lightsludge from the housing to a disposal container.
 109. The method ofclaim 104 further comprising the step of:withdrawing solids remaining inthe treated solution storage tank from the treated solution storage tankand passing the solids to a disposal container.
 110. The method of claim104 further comprising the step of:withdrawing solids remaining in theparts washer assembly from the parts washer assembly and passing thesolids to a disposal container.
 111. The method of claim 104 furthercomprising the steps of:injecting a volume of treated aqueous surfactantsolution from the treated solution storage tank into the parts washerassembly at a sufficient pressure to flush the parts washer assembly;removing the flushing aqueous surfactant solution from the parts washerassembly for passage into the mixing zone in the housing; and passing avolume of the treated aqueous surfactant solution suitable for operatingthe parts washer assembly from the treated solution storage tank to theparts washer assembly.
 112. The method of claim 104 further comprisingthe steps of:operating the parts washer assembly; and concurrentlypassing contaminated aqueous surfactant solution from the parts washerassembly into the mixing zone and treated aqueous surfactant solutionfrom the treated solution storage tank such that the parts washerassembly is operating while the contaminated aqueous surfactant solutionis being passed through the housing.
 113. A method for recycling acontaminated aqueous surfactant solution of an apparatus comprising thesteps of:(a) passing the contaminated aqueous surfactant solution fromthe apparatus into a mixing zone in a housing; (b) introducing air intothe contaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone in anamount sufficient so that large air bubbles are formed in thecontaminated aqueous surfactant solution in the mixing zone; (c)introducing water into the mixing zone so that the water contacts thelarge air bubbles formed in the contaminated aqueous surfactant solutionin the mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (d) passing the contaminated aqueous surfactant solution from themixing zone into a quiescent zone in the housing where the contaminatedaqueous surfactant solution is separated into an upper layer containinglight sludge, an intermediate layer constituting a treated aqueoussurfactant solution and a lower layer containing a heavy sludge; (e)passing the treated aqueous surfactant solution from the quiescent zoneinto a discharge zone in the housing; and (f) passing the treatedaqueous surfactant solution from the discharge zone to a treated aqueoussurfactant solution storage tank.
 114. The method of claim 113 furthercomprising the steps of:prior to step (f), recovering the treatedaqueous surfactant solution from the discharge zone in the housing andrepeating steps (b)-(e) until the treated aqueous surfactant solution issubstantially free of oils, particulate matter and dissolved heavymetals.
 115. The method of claim 113 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone.
 116. The method of claim113 further comprising the step of:passing the heavy sludge from thehousing to a disposal container.
 117. The method of claim 113 furthercomprising the step of:skimming the light sludge from the housing; andpassing the light sludge from the housing to a disposal container. 118.The method of claim 113 further comprising the step of:withdrawingsolids remaining in the treated solution storage tank from the treatedsolution storage tank and passing the solids to a disposal container.119. The method of claim 113 further comprising the step of:withdrawingsolids remaining in the apparatus from the apparatus and passing thesolids to a disposal container.
 120. The method of claim 113 furthercomprising the steps of:injecting a volume of treated aqueous surfactantsolution from the treated solution storage tank into the apparatus at asufficient pressure to flush the apparatus; removing the flushingaqueous surfactant solution from the apparatus for passage into themixing zone in the housing; and passing a volume of the treated aqueoussurfactant solution suitable for operating the apparatus from thetreated solution storage tank to the apparatus.
 121. The method of claim113 further comprising the steps of:operating the parts washer assembly;and concurrently passing contaminated aqueous surfactant solution fromthe parts washer assembly into the mixing zone of the housing andtreated aqueous surfactant solution from the treated solution storagetank such that the parts washer assembly is operating while the aqueoussurfactant solution is being passed through the housing.
 122. A methodfor recycling a contaminated aqueous surfactant solution of anapparatus, comprising the steps of:(a) passing the contaminated aqueoussurfactant solution from the apparatus into a mixing zone in a housing;(b) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone in an amount sufficient so that large air bubblesare formed in the contaminated aqueous surfactant solution in the mixingzone; (c) spraying water onto the contaminated aqueous surfactantsolution in the mixing zone so that the sprayed water contacts the largeair bubbles formed in the contaminated aqueous surfactant solution inthe mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (d) passing the contaminated aqueous surfactant solution from themixing zone into a quiescent zone in the housing where the contaminatedaqueous surfactant solution is separated into an upper layer containinglight sludge, an intermediate layer constituting a treated aqueoussurfactant solution and a lower layer containing a heavy sludge; (e)passing the treated aqueous surfactant solution from the quiescent zoneinto a discharge zone in the housing; and (f) passing the treatedaqueous surfactant solution from the discharge zone to a treated aqueoussurfactant solution storage tank.
 123. The method of claim 122 furthercomprising the step of:prior to step (f), recovering the treated aqueoussurfactant solution from the discharge zone in the housing and repeatingsteps (b)-(e) until the treated aqueous surfactant solution issubstantially free of oils, particulate matter and dissolved heavymetals.
 124. The method of claim 122 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the aqueous surfactant solution beingintroduced into the mixing zone.
 125. The method of claim 122 furthercomprising the step of:passing the heavy sludge from the housing to adisposal container.
 126. The method of claim 122 further comprising thestep of:skimming the light sludge from the housing; and passing thelight sludge from the housing to a disposal container.
 127. The methodof claim 122 further comprising the step of:withdrawing solids remainingin the treated solution storage tank from the treated solution storagetank and passing the solids to a disposal container.
 128. The method ofclaim 122 further comprising the step of:withdrawing solids remaining inthe apparatus from the apparatus and passing the solids to a disposalcontainer.
 129. The method of claim 122 further comprising the stepsof:injecting a volume of treated aqueous surfactant solution from thetreated solution storage tank into the apparatus at a sufficientpressure to flush the apparatus; removing the flushing aqueoussurfactant solution from the apparatus for passage into the mixing zonein the housing; and passing a volume of the treated aqueous surfactantsolution suitable for operating the apparatus from the treated solutionstorage tank to the apparatus.
 130. The method of claim 122 furthercomprising the steps of:operating the apparatus; and concurrentlypassing aqueous surfactant solution from the apparatus into the mixingzone of the housing and treated aqueous surfactant solution from thetreated solution storage tank such that the apparatus is operating whilethe aqueous surfactant solution is being passed through the housing.131. A method for recycling a contaminated aqueous surfactant solutionof a parts washer assembly, comprising the steps of:(a) passing thecontaminated aqueous surfactant solution from the parts washer assemblyto a contaminated solution storage tank; (b) accumulating a volume ofthe contaminated aqueous surfactant solution in the contaminatedsolution storage tank; (c) passing the accumulated contaminated aqueoussurfactant solution from the contaminated solution storage tank into amixing zone in a housing; (d) introducing air into the contaminatedaqueous surfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone in an amount sufficientso that large air bubbles are formed in the aqueous surfactant solutionin the mixing zone; (e) spraying water onto the contaminated aqueoussurfactant solution in the mixing zone so that the sprayed watercontacts the large air bubbles formed in the contaminated aqueoussurfactant solution in the mixing zone and substantially reduces thesize of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (f) passing the contaminated aqueoussurfactant solution from the mixing zone into a quiescent zone in thehousing where the contaminated aqueous surfactant solution is separatedinto an upper layer containing light sludge, an intermediate layerconstituting a treated aqueous surfactant solution and a lower layercontaining a heavy sludge; (g) passing the treated aqueous surfactantsolution from the quiescent zone into a discharge zone in the housing;and (h) recovering the treated aqueous surfactant solution from thedischarge zone of the housing for recycle to the parts washer.
 132. Themethod of claim 131 further comprising the steps of:prior to step (h),(i) passing the treated aqueous surfactant solution from the dischargezone of the housing to the contaminated solution storage tank; repeatingsteps (c)-(g) and (i) until the treated aqueous surfactant issubstantially free of oils, particulate matter and dissolved heavymetals.
 133. The method of claim 131 further comprising the stepof:introducing a chemical treating agent into the aqueous surfactantsolution prior to the aqueous surfactant solution being introduced intothe mixing zone.
 134. The method of claim 131 further comprising thestep of:passing the heavy sludge from the housing to a disposalcontainer.
 135. The method of claim 131 further comprising the stepof:skimming the light sludge from the housing; and passing the lightsludge from the housing to a disposal container.
 136. The method ofclaim 131 further comprising the step of:withdrawing solids remaining inthe contaminated solution storage tank from the contaminated solutionstorage tank and passing the solids to a disposal container.
 137. Themethod of claim 131 further comprising the step of:withdrawing solidsremaining in the parts washer assembly from the parts washer assemblyand passing the solids to a disposal container.
 138. The method of claim131 further comprising the steps of:monitoring the amount of thecontaminated aqueous surfactant solution accumulated in the contaminatedsolution storage tank; and selectively passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank to the housing when a predetermined amount of contaminatedaqueous surfactant solution has accumulated in the contaminated solutionstorage tank.
 139. The method of claim 131 further comprising the stepsof:injecting a volume of treated aqueous surfactant solution recoveredfrom the discharge zone of the housing into the parts washer assembly ata sufficient pressure to flush the parts washer assembly; passing theflushing aqueous surfactant solution from the parts washer assembly tothe contaminated solution storage tank; and passing a volume of thetreated aqueous surfactant solution suitable for operating the partswasher assembly recovered from the discharge zone of the housing to theparts washer assembly.
 140. The method of claim 131 further comprisingthe steps of:operating the parts washer assembly; and concurrentlypassing the accumulated contaminated aqueous surfactant solution fromthe contaminated solution storage tank into the mixing zone of thehousing such that the parts washer assembly is operating while thecontaminated aqueous surfactant solution is being passed through thehousing.
 141. A method for recycling a contaminated aqueous surfactantsolution of a parts washer assembly, comprising the steps of:(a) passingthe contaminated aqueous surfactant solution from the parts washerassembly to a contaminated solution storage tank; (b) accumulating avolume of the contaminated aqueous surfactant solution in thecontaminated solution storage tank; (c) selectively connecting aportable housing having a fluid inlet and a fluid outlet to thecontaminated solution storage tank and a treated solution storage tanksuch that the fluid inlet of the housing is in fluid communication withthe contaminated solution storage tank and the fluid outlet of thehousing is in fluid communication with the treated solution storagetank, the housing having a mixing zone, a quiescent zone and a dischargezone; (d) passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing via the fluid inlet; (e) introducing air into thecontaminated aqueous surfactant solution prior to the aqueous surfactantsolution being introduced into the mixing zone in an amount sufficientso that large air bubbles are formed in the contaminated aqueoussurfactant solution in the mixing zone; (f) spraying water onto thecontaminated aqueous surfactant solution in the mixing zone so that thesprayed water contacts the large air bubbles formed in the contaminatedaqueous surfactant solution in the mixing zone and substantially reducesthe size of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (g) passing the contaminated aqueoussurfactant solution from the mixing zone into the quiescent zone wherethe contaminated aqueous surfactant solution is separated into an upperlayer containing light sludge, an intermediate layer constituting atreated aqueous surfactant solution and a lower layer containing a heavysludge; (h) passing the treated aqueous surfactant solution from thequiescent zone into the discharge zone of the housing; and (i)recovering the treated aqueous surfactant solution from the dischargezone of the housing for recycle to the parts washer.
 142. The method ofclaim 141 further comprising the steps of:(j) connecting the dischargezone of the housing to the contaminated solution storage tank such thatthe fluid outlet of the housing is in fluid communication with thecontaminated solution storage tank; (k) prior to step (i), passing thetreated aqueous surfactant solution from the discharge zone to thecontaminated solution storage tank; (l) repeating steps (c)-(h) and (k)until the treated aqueous surfactant solution is substantially free ofoils, particulate matter and dissolved heavy metals.
 143. The method ofclaim 141 further comprising the step of:introducing a chemical treatingagent into the contaminated aqueous surfactant solution prior to thecontaminated aqueous surfactant solution being introduced into themixing zone.
 144. The method of claim 141 further comprising the stepof:selectively passing the heavy sludge from the housing to a disposalcontainer.
 145. The method of claim 141 further comprising the stepof:skimming the light sludge from the quiescent zone; and selectivelypassing the light sludge to a disposal container.
 146. The method ofclaim 141 further comprising the step of:selectively passing solidsdisposed in the contaminated solution storage tank from the contaminatedsolution storage tank to a disposal container.
 147. The method of claim141 further comprising the step of:selectively passing solids disposedin the parts washer assembly from the parts washer assembly to adisposal container.
 148. The method of claim 141 further comprising thesteps of:monitoring the amount of the contaminated aqueous surfactantsolution accumulated in the contaminated solution storage tank; andselectively passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank to the housing whena predetermined amount of contaminated aqueous surfactant solution hasaccumulated in the contaminated solution storage tank.
 149. The methodof claim 141 further comprising the steps of:injecting a volume oftreated aqueous surfactant solution recovered from the discharge zone ofthe housing into the parts washer assembly at a sufficient pressure toflush the parts washer assembly; passing the flushing aqueous surfactantsolution from the parts washer assembly to the contaminated solutionstorage tank; and passing a volume of the treated aqueous surfactantsolution suitable for operating the parts washer assembly recovered fromthe discharge zone of the housing to the parts washer assembly.
 150. Themethod of claim 141 further comprising the steps of:operating the partswasher assembly; and concurrently passing the accumulated contaminatedaqueous surfactant solution from the contaminated solution storage tankinto the mixing zone of the housing such that the parts washer assemblyis operating while the contaminated aqueous surfactant solution is beingpassed through the housing.
 151. A method for recycling contaminatedaqueous surfactant solution from a plurality of parts washer assemblies,comprising the steps of:(a) providing each of the parts washerassemblies with a contaminated solution storage tank which is in fluidcommunication with the parts washer assembly; (b) selectively passingthe contaminated aqueous surfactant solution from each of the partswasher assemblies to the contaminated solution storage tank in fluidcommunication therewith; (c) accumulating a volume of the contaminatedaqueous surfactant solution in the contaminated solution storage tanks;(d) selectively connecting a portable housing having a fluid inlet and afluid outlet to one of the contaminated solution storage tanks such thatthe fluid inlet of the housing is in fluid communication with thecontaminated solution storage tank, the housing having a mixing zone, aquiescent zone and a discharge zone; (e) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing via the fluid inlet;(f) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone of the housing in an amount sufficient so thatlarge air bubbles are formed in the contaminated aqueous surfactantsolution in the mixing zone; (g) spraying water onto the contaminatedaqueous surfactant solution in the mixing zone so that the sprayed watercontacts the large air bubbles formed in the contaminated aqueoussurfactant solution in the mixing zone and substantially reduces thesize of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (h) passing the contaminated aqueoussurfactant solution from the mixing zone into the quiescent zone wherethe contaminated aqueous surfactant solution is separated into an upperlayer containing light sludge, an intermediate layer constituting atreated aqueous surfactant solution and a lower layer containing a heavysludge; (i) passing the treated aqueous surfactant solution from thequiescent zone into the discharge zone; (j) recovering the treatedaqueous surfactant solution from the discharge zone in the housing forrecycle to the parts washer assembly; and (k) repeating steps (d)-(j)for the contaminated solution storage tanks of each parts washerassembly.
 152. The method of claim 151 further comprising the stepsof:(l) connecting the discharge zone of the housing to the contaminatedsolution storage tank such that the fluid outlet of the housing is influid communication with the contaminated solution storage tank; (m)prior to step (j), passing the treated aqueous surfactant solution fromthe discharge zone to the contaminated solution storage tank; (n)repeating steps (d)-(i) and (m) until the treated aqueous surfactantsolution is substantially free of oils, particulate matter and dissolvedheavy metals.
 153. The method of claim 151 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone of the housing.
 154. Themethod of claim 151 further comprising the step of:selectively passingthe heavy sludge from the housing to a disposal container.
 155. Themethod of claim 151 further comprising the steps of:skimming the lightsludge from the quiescent zone; and selectively passing the light sludgeto a disposal container.
 156. The method of claim 151 further comprisingthe step of:selectively passing solids disposed in the contaminatedsolution storage tank from the contaminated solution storage tank to adisposal container.
 157. The method of claim 151 further comprising thestep of:selectively passing solids disposed in the parts washerassemblies from the parts washer assemblies to a disposal container.158. The method of claim 151 further comprising the steps of:monitoringthe amount of the contaminated aqueous surfactant solution accumulatedin the contaminated solution storage tank; and selectively passing theaccumulated contaminated aqueous surfactant solution from thecontaminated solution storage tank to the housing when a predeterminedamount of contaminated aqueous surfactant solution has accumulated inthe contaminated solution storage tank.
 159. The method of claim 151further comprising the steps of:injecting a volume of treated aqueoussurfactant solution recovered from the discharge zone of the housinginto the parts washer assembly at a sufficient pressure to flush theparts washer assembly; passing the flushing aqueous surfactant solutionfrom the parts washer assembly to the contaminated solution storagetank; and passing a volume of the treated aqueous surfactant solutionsuitable for operating the parts washer assembly recovered from thedischarge zone of the housing to the parts washer assembly.
 160. Themethod of claim 151 further comprising the steps of:operating the partswasher assembly; and concurrently passing the accumulated contaminatedaqueous surfactant solution from the contaminated solution storage tankinto the mixing zone of the housing such that the parts washer assemblyis operating while the contaminated aqueous surfactant solution is beingpassed through the housing.
 161. A method for recycling a contaminatedaqueous surfactant solution of a parts washer assembly, comprising thesteps of:(a) passing the contaminated aqueous surfactant solution fromthe parts washer assembly to a contaminated solution storage tank; (b)accumulating a volume of the contaminated aqueous surfactant solution inthe contaminated solution storage tank; (c) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into a mixing zone in a housing; (d) introducing air intothe contaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone in anamount sufficient so that large air bubbles are formed in thecontaminated aqueous surfactant solution in the mixing zone; (e)introducing water into the mixing zone so that the water contacts thelarge air bubbles formed in the contaminated aqueous surfactant solutionin the mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (f) passing the contaminated aqueous surfactant solution from themixing zone into a quiescent zone in the housing where the contaminatedaqueous surfactant solution is separated into an upper layer containinglight sludge, an intermediate layer constituting a treated aqueoussurfactant solution and a lower layer containing a heavy sludge; (g)passing the treated aqueous surfactant solution from the quiescent zoneinto a discharge zone in the housing; and (h) recovering the treatedaqueous surfactant solution from the discharge zone of the housing forrecycle to the parts washer.
 162. The method of claim 161 furthercomprising the steps of:prior to step (h), (i) passing the treatedaqueous surfactant solution from the discharge zone of the housing tothe contaminated solution storage tank; repeating steps (c)-(g) and (i)until the treated aqueous surfactant is substantially free of oils,particulate matter and dissolved heavy metals.
 163. The method of claim161 further comprising the step of:introducing a chemical treating agentinto the contaminated aqueous surfactant solution prior to thecontaminated aqueous surfactant solution being introduced into themixing zone.
 164. The method of claim 161 further comprising the stepof:passing the heavy sludge from the housing to a disposal container.165. The method of claim 161 further comprising the step of:skimming thelight sludge from the housing; and passing the light sludge from thehousing to a disposal container.
 166. The method of claim 161 furthercomprising the step of:withdrawing solids remaining in the contaminatedsolution storage tank from the contaminated solution storage tank andpassing the solids to a disposal container.
 167. The method of claim 161further comprising the step of:withdrawing solids remaining in the partswasher assembly from the parts washer assembly and passing the solids toa disposal container.
 168. The method of claim 161 further comprisingthe steps of:monitoring the amount of the contaminated aqueoussurfactant solution accumulated in the contaminated solution storagetank; and selectively passing the accumulated contaminated aqueoussurfactant solution from the contaminated solution storage tank to thehousing when a predetermined amount of contaminated aqueous surfactantsolution has accumulated in the contaminated solution storage tank. 169.The method of claim 161 further comprising the steps of:injecting avolume of treated aqueous surfactant solution recovered from thedischarge zone of the housing into the parts washer assembly at asufficient pressure to flush the parts washer assembly; passing theflushing aqueous surfactant solution from the parts washer assembly tothe contaminated solution storage tank; and passing a volume of thetreated aqueous surfactant solution suitable for operating the partswasher assembly recovered from the discharge zone of the housing to theparts washer assembly.
 170. The method of claim 161 further comprisingthe steps of:operating the parts washer assembly; and concurrentlypassing the accumulated contaminated aqueous surfactant solution fromthe contaminated solution storage tank into the mixing zone of thehousing such that the parts washer assembly is operating while thecontaminated aqueous surfactant solution is being passed through thehousing.
 171. A method for recycling a contaminated aqueous surfactantsolution of a parts washer assembly, comprising the steps of:(a) passingthe contaminated aqueous surfactant solution from the parts washerassembly to a contaminated solution storage tank; (b) accumulating avolume of the contaminated aqueous surfactant solution in thecontaminated solution storage tank; (c) selectively connecting aportable housing having a fluid inlet and a fluid outlet to thecontaminated solution storage tank and a treated solution storage tanksuch that the fluid inlet of the housing is in fluid communication withthe contaminated solution storage tank and the fluid outlet of thehousing is in fluid communication with the treated solution storagetank, the housing having a mixing zone, a quiescent zone and a dischargezone; (d) passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing via the fluid inlet; (e) introducing air into thecontaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone in anamount sufficient so that large air bubbles are formed in thecontaminated aqueous surfactant solution in the mixing zone; (f)introducing water into the mixing zone so that the water contacts thelarge air bubbles formed in the contaminated aqueous surfactant solutionin the mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (g) passing the contaminated aqueous surfactant solution from themixing zone into the quiescent zone where the contaminated aqueoussurfactant solution is separated into an upper layer containing lightsludge, an intermediate layer constituting a treated aqueous surfactantsolution and a lower layer containing a heavy sludge; (h) passing thetreated aqueous surfactant solution from the quiescent zone into thedischarge zone of the housing; and (i) recovering the treated aqueoussurfactant solution from the discharge zone of the housing for recycleto the parts washer.
 172. The method of claim 171 further comprising thesteps of:(j) connecting the discharge zone of the housing to thecontaminated solution storage tank such that the fluid outlet of thehousing is in fluid communication with the contaminated solution storagetank; (k) prior to step (i), passing the treated aqueous surfactantsolution from the discharge zone to the contaminated solution storagetank; (l) repeating steps (c)-(h) and (k) until the treated aqueoussurfactant solution is substantially free of oils, particulate matterand dissolved heavy metals.
 173. The method of claim 171 furthercomprising the step of:introducing a chemical treating agent into thecontaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone. 174.The method of claim 171 further comprising the step of:selectivelypassing the heavy sludge from the housing to a disposal container. 175.The method of claim 171 further comprising the step of:skimming thelight sludge from the quiescent zone; and selectively passing the lightsludge to a disposal container.
 176. The method of claim 171 furthercomprising the step of:selectively passing solids disposed in thecontaminated solution storage tank from the contaminated solutionstorage tank to a disposal container.
 177. The method of claim 171further comprising the step of:selectively passing solids disposed inthe parts washer assembly from the parts washer assembly to a disposalcontainer.
 178. The method of claim 171 further comprising the stepsof:monitoring the amount of the contaminated aqueous surfactant solutionaccumulated in the contaminated solution storage tank; and selectivelypassing the accumulated contaminated aqueous surfactant solution fromthe contaminated solution storage tank to the housing when apredetermined amount of contaminated aqueous surfactant solution hasaccumulated in the contaminated solution storage tank.
 179. The methodof claim 171 further comprising the steps of:injecting a volume oftreated aqueous surfactant solution recovered from the discharge zone ofthe housing into the parts washer assembly at a sufficient pressure toflush the parts washer assembly; passing the flushing aqueous surfactantsolution from the parts washer assembly to the contaminated solutionstorage tank; and passing a volume of the treated aqueous surfactantsolution suitable for operating the parts washer assembly recovered fromthe discharge zone of the housing to the parts washer assembly.
 180. Themethod of claim 171 further comprising the steps of:operating the partswasher assembly; and concurrently passing the accumulated contaminatedaqueous surfactant solution from the contaminated solution storage tankinto the mixing zone of the housing such that the parts washer assemblyis operating while the contaminated aqueous surfactant solution is beingpassed through the housing.
 181. A method for recycling contaminatedaqueous surfactant solution from a plurality of parts washer assemblies,comprising the steps of:(a) providing each of the parts washerassemblies with a contaminated solution storage tank which is in fluidcommunication with the parts washer assembly; (b) selectively passingthe contaminated aqueous surfactant solution from each of the partswasher assemblies to the contaminated solution storage tank in fluidcommunication therewith; (c) accumulating a volume of the contaminatedaqueous surfactant solution in the contaminated solution storage tanks;(d) selectively connecting a portable housing having a fluid inlet and afluid outlet to one of the contaminated solution storage tanks such thatthe fluid inlet of the housing is in fluid communication with thecontaminated solution storage tank, the housing having a mixing zone, aquiescent zone and a discharge zone; (e) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing via the fluid inlet;(f) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone of the housing in an amount sufficient so thatlarge air bubbles are formed in the contaminated aqueous surfactantsolution in the mixing zone; (g) introducing water into the mixing zoneof the housing so that the water contacts the large air bubbles formedin the contaminated aqueous surfactant solution in the mixing zone andsubstantially reduces the size of the large air bubbles in thecontaminated aqueous surfactant solution in the mixing zone; (h) passingthe contaminated aqueous surfactant solution from the mixing zone intothe quiescent zone where the contaminated aqueous surfactant solution isseparated into an upper layer containing light sludge, an intermediatelayer constituting a treated aqueous surfactant solution and a lowerlayer containing a heavy sludge; (i) passing the treated aqueoussurfactant solution from the quiescent zone into the discharge zone; (j)recovering the treated aqueous surfactant solution from the dischargezone in the housing for recycle to the parts washer assembly; and (k)repeating steps (d)-(j) for the contaminated solution storage tanks ofeach parts washer assembly.
 182. The method of claim 181 furthercomprising the steps of:(l) connecting the discharge zone of the housingto the contaminated solution storage tank such that the fluid outlet ofthe housing is in fluid communication with the contaminated solutionstorage tank; (m) prior to step (j), passing the treated aqueoussurfactant solution from the discharge zone to the contaminated solutionstorage tank; (n) repeating steps (d)-(i) and (m) until the treatedaqueous surfactant solution is substantially free of oils, particulatematter and dissolved heavy metals.
 183. The method of claim 181 furthercomprising the step of:introducing a chemical treating agent into thecontaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone of thehousing.
 184. The method of claim 181 further comprising the stepof:selectively passing the heavy sludge from the housing to a disposalcontainer.
 185. The method of claim 181 further comprising the stepsof:skimming the light sludge from the quiescent zone; and selectivelypassing the light sludge to a disposal container.
 186. The method ofclaim 181 further comprising the step of:selectively passing solidsdisposed in the contaminated solution storage tank from the contaminatedsolution storage tank to a disposal container.
 187. The method of claim181 further comprising the step of:selectively passing solids disposedin the parts washer assemblies from the parts washer assemblies to adisposal container.
 188. The method of claim 181 further comprising thesteps of:monitoring the amount of the contaminated aqueous surfactantsolution accumulated in the contaminated solution storage tank; andselectively passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank to the housing whena predetermined amount of contaminated aqueous surfactant solution hasaccumulated in the contaminated solution storage tank.
 189. The methodof claim 181 further comprising the steps of:injecting a volume oftreated aqueous surfactant solution recovered from the discharge zone ofthe housing into the parts washer assembly at a sufficient pressure toflush the parts washer assembly; passing the flushing aqueous surfactantsolution from the parts washer assembly to the contaminated solutionstorage tank; and passing a volume of the treated aqueous surfactantsolution suitable for operating the parts washer assembly recovered fromthe discharge zone of the housing to the parts washer assembly.
 190. Themethod of claim 181 further comprising the steps of:operating the partswasher assembly; and concurrently passing the accumulated contaminatedaqueous surfactant solution from the contaminated solution storage tankinto the mixing zone of the housing such that the parts washer assemblyis operating while the contaminated aqueous surfactant solution is beingpassed through the housing.
 191. A method for recycling a contaminatedaqueous surfactant solution of an apparatus, comprising the steps of:(a)passing the contaminated aqueous surfactant solution from the apparatusto a contaminated solution storage tank; (b) accumulating a volume ofthe contaminated aqueous surfactant solution in the contaminatedsolution storage tank; (c) passing the accumulated contaminated aqueoussurfactant solution from the contaminated solution storage tank into amixing zone in a housing; (d) introducing air into the contaminatedaqueous surfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone in an amount sufficientso that large air bubbles are formed in the contaminated aqueoussurfactant solution in the mixing zone; (e) spraying water onto thecontaminated aqueous surfactant solution in the mixing zone so that thesprayed water contacts the large air bubbles formed in the contaminatedaqueous surfactant solution in the mixing zone and substantially reducesthe size of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (f) passing the contaminated aqueoussurfactant solution from the mixing zone into a quiescent zone in thehousing where the contaminated aqueous surfactant solution is separatedinto an upper layer containing light sludge, an intermediate layerconstituting a treated aqueous surfactant solution and a lower layercontaining a heavy sludge; (g) passing the treated aqueous surfactantsolution from the quiescent zone into a discharge zone in the housing;and (h) recovering the treated aqueous surfactant solution from thedischarge zone of the housing for recycle to the apparatus.
 192. Themethod of claim 191 further comprising the steps of:prior to step (h),(i) passing the treated aqueous surfactant solution from the dischargezone of the housing to the contaminated solution storage tank; repeatingsteps (c)-(g) and (i) until the treated aqueous surfactant issubstantially free of oils, particulate matter and dissolved heavymetals.
 193. The method of claim 191 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone.
 194. The method of claim191 further comprising the step of:passing the heavy sludge from thehousing to a disposal container.
 195. The method of claim 191 furthercomprising the step of:skimming the light sludge from the housing; andpassing the light sludge from the housing to a disposal container. 196.The method of claim 191 further comprising the step of:withdrawingsolids remaining in the contaminated solution storage tank from thecontaminated solution storage tank and passing the solids to a disposalcontainer.
 197. The method of claim 191 further comprising the stepof:withdrawing solids remaining in the apparatus from the apparatus andpassing the solids to a disposal container.
 198. The method of claim 191further comprising the steps of:monitoring the amount of thecontaminated aqueous surfactant solution accumulated in the contaminatedsolution storage tank; and selectively passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank to the housing when a predetermined amount of contaminatedaqueous surfactant solution has accumulated in the contaminated solutionstorage tank.
 199. The method of claim 191 further comprising the stepsof:injecting a volume of treated aqueous surfactant solution recoveredfrom the discharge zone of the housing into the apparatus at asufficient pressure to flush the apparatus; passing the flushing aqueoussurfactant solution from the apparatus to the contaminated solutionstorage tank; and passing a volume of the treated aqueous surfactantsolution suitable for operating the apparatus recovered from thedischarge zone of the housing to the apparatus.
 200. The method of claim191 further comprising the steps of:operating the apparatus; andconcurrently passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing such that the apparatus is operating while thecontaminated aqueous surfactant solution is being passed through thehousing.
 201. A method for recycling a contaminated aqueous surfactantsolution of an apparatus, comprising the steps of:(a) passing thecontaminated aqueous surfactant solution from the apparatus to acontaminated solution storage tank; (b) accumulating a volume of thecontaminated aqueous surfactant solution in the contaminated solutionstorage tank; (c) selectively connecting a portable housing having afluid inlet and a fluid outlet to the contaminated solution storage tankand a treated solution storage tank such that the fluid inlet of thehousing is in fluid communication with the contaminated solution storagetank and the fluid outlet of the housing is in fluid communication withthe treated solution storage tank, the housing having a mixing zone, aquiescent zone and a discharge zone; (d) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing via the fluid inlet;(e) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone in an amount sufficient so that large air bubblesare formed in the contaminated aqueous surfactant solution in the mixingzone; (f) spraying water onto the contaminated aqueous surfactantsolution in the mixing zone so that the sprayed water contacts the largeair bubbles formed in the contaminated aqueous surfactant solution inthe mixing zone and substantially reduces the size of the large airbubbles in the contaminated aqueous surfactant solution in the mixingzone; (g) passing the contaminated aqueous surfactant solution from themixing zone into the quiescent zone where the contaminated aqueoussurfactant solution is separated into an upper layer containing lightsludge, an intermediate layer constituting a treated aqueous surfactantsolution and a lower layer containing a heavy sludge; (h) passing thetreated aqueous surfactant solution from the quiescent zone into thedischarge zone of the housing; and (i) recovering the treated aqueoussurfactant solution from the discharge zone of the housing for recycleto the apparatus.
 202. The method of claim 201 further comprising thesteps of:(j) connecting the discharge zone of the housing to thecontaminated solution storage tank such that the fluid outlet of thehousing is in fluid communication with the contaminated solution storagetank; (k) prior to step (i), passing the treated aqueous surfactantsolution from the discharge zone to the contaminated solution storagetank; (l) repeating steps (c)-(h) and (k) until the treated aqueoussurfactant solution is substantially free of oils, particulate matterand dissolved heavy metals.
 203. The method of claim 201 furthercomprising the step of:introducing a chemical treating agent into thecontaminated aqueous surfactant solution prior to the contaminatedaqueous surfactant solution being introduced into the mixing zone. 204.The method of claim 201 further comprising the step of:selectivelypassing the heavy sludge from the housing to a disposal container. 205.The method of claim 201 further comprising the step of:skimming thelight sludge from the quiescent zone; and selectively passing the lightsludge to a disposal container.
 206. The method of claim 201 furthercomprising the step of:selectively passing solids disposed in thecontaminated solution storage tank from the contaminated solutionstorage tank to a disposal container.
 207. The method of claim 201further comprising the step of:selectively passing solids disposed inthe apparatus from the apparatus to a disposal container.
 208. Themethod of claim 201 further comprising the steps of:monitoring theamount of the contaminated aqueous surfactant solution accumulated inthe contaminated solution storage tank; and selectively passing theaccumulated contaminated aqueous surfactant solution from thecontaminated solution storage tank to the housing when a predeterminedamount of contaminated aqueous surfactant solution has accumulated inthe contaminated solution storage tank.
 209. The method of claim 201further comprising the steps of:injecting a volume of treated aqueoussurfactant solution recovered from the discharge zone of the housinginto the apparatus at a sufficient pressure to flush the apparatus;passing the flushing aqueous surfactant solution from the apparatus tothe contaminated solution storage tank; and passing a volume of thetreated aqueous surfactant solution suitable for operating the apparatusrecovered from the discharge zone of the housing to the apparatus. 210.The method of claim 201 further comprising the steps of:operating theapparatus; and concurrently passing the accumulated contaminated aqueoussurfactant solution from the contaminated solution storage tank into themixing zone of the housing such that the apparatus is operating whilethe contaminated aqueous surfactant solution is being passed through thehousing.
 211. A method for recycling contaminated aqueous surfactantsolution from a plurality of apparatus, comprising the steps of:(a)providing each of the apparatus with a contaminated solution storagetank which is in fluid communication with the apparatus; (b) selectivelypassing the contaminated aqueous surfactant solution from each of theapparatus to the contaminated solution storage tank in fluidcommunication therewith; (c) accumulating a volume of the contaminatedaqueous surfactant solution in the contaminated solution storage tanks;(d) selectively connecting a portable housing having a fluid inlet and afluid outlet to one of the contaminated solution storage tanks such thatthe fluid inlet of the housing is in fluid communication with thecontaminated solution storage tank, the housing having a mixing zone, aquiescent zone and a discharge zone; (e) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing via the fluid inlet;(f) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone of the housing in an amount sufficient so thatlarge air bubbles are formed in the contaminated aqueous surfactantsolution in the mixing zone; (g) spraying water onto the contaminatedaqueous surfactant solution in the mixing zone so that the sprayed watercontacts the large air bubbles formed in the contaminated aqueoussurfactant solution in the mixing zone and substantially reduces thesize of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (h) passing the contaminated aqueoussurfactant solution from the mixing zone into the quiescent zone wherethe contaminated aqueous surfactant solution is separated into an upperlayer containing light sludge, an intermediate layer constituting atreated aqueous surfactant solution and a lower layer containing a heavysludge; (i) passing the treated aqueous surfactant solution from thequiescent zone into the discharge zone; (j) recovering the treatedaqueous surfactant solution from the discharge zone in the housing forrecycle to the apparatus; and (k) repeating steps (d)-(j) for thecontaminated solution storage tanks of each apparatus.
 212. The methodof claim 211 further comprising the steps of:(l) connecting thedischarge zone of the housing to the contaminated solution storage tanksuch that the fluid outlet of the housing is in fluid communication withthe contaminated solution storage tank; (m) prior to step (j), passingthe treated aqueous surfactant solution from the discharge zone to thecontaminated solution storage tank; (n) repeating steps (d)-(i) and (m)until the treated aqueous surfactant solution is substantially free ofoils, particulate matter and dissolved heavy metals.
 213. The method ofclaim 212 further comprising the step of:introducing a chemical treatingagent into the contaminated aqueous surfactant solution prior to thecontaminated aqueous surfactant solution being introduced into themixing zone of the housing.
 214. The method of claim 212 furthercomprising the step of:selectively passing the heavy sludge from thehousing to a disposal container.
 215. The method of claim 212 furthercomprising the steps of:skimming the light sludge from the quiescentzone; and selectively passing the light sludge to a disposal container.216. The method of claim 212 further comprising the step of:selectivelypassing solids disposed in the contaminated solution storage tank fromthe contaminated solution storage tank to a disposal container.
 217. Themethod of claim 211 further comprising the step of:selectively passingsolids disposed in the apparatus from the apparatus to a disposalcontainer.
 218. The method of claim 211 further comprising the stepsof:monitoring the amount of the contaminated aqueous surfactant solutionaccumulated in the contaminated solution storage tank; and selectivelypassing the accumulated contaminated aqueous surfactant solution fromthe contaminated solution storage tank to the housing when apredetermined amount of contaminated aqueous surfactant solution hasaccumulated in the contaminated solution storage tank.
 219. The methodof claim 211 further comprising the steps of:injecting a volume oftreated aqueous surfactant solution recovered from the discharge zone ofthe housing into the apparatus at a sufficient pressure to flush theapparatus; passing the flushing aqueous surfactant solution from theapparatus to the contaminated solution storage tank; and passing avolume of the treated aqueous surfactant solution suitable for operatingthe apparatus recovered from the discharge zone of the housing to theapparatus.
 220. The method of claim 211 further comprising the stepsof:operating the apparatus; and concurrently passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing such that the apparatusis operating while the contaminated aqueous surfactant solution is beingpassed through the housing.
 221. A method for recycling a contaminatedaqueous surfactant solution of an apparatus, comprising the steps of:(a)passing the contaminated aqueous surfactant solution from the apparatusto a contaminated solution storage tank; (b) accumulating a volume ofthe contaminated aqueous surfactant solution in the contaminatedsolution storage tank; (c) passing the accumulated contaminated aqueoussurfactant solution from the contaminated solution storage tank into amixing zone in a housing; (d) introducing air into the contaminatedaqueous surfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone in an amount sufficientso that large air bubbles are formed in the aqueous surfactant solutionin the mixing zone; (e) introducing water into the mixing zone so thatthe water contacts the large air bubbles formed in the contaminatedaqueous surfactant solution in the mixing zone and substantially reducesthe size of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (f) passing the contaminated aqueoussurfactant solution from the mixing zone into a quiescent zone in thehousing where the contaminated aqueous surfactant solution is separatedinto an upper layer containing light sludge, an intermediate layerconstituting a treated aqueous surfactant solution and a lower layercontaining a heavy sludge; (g) passing the treated aqueous surfactantsolution from the quiescent zone into a discharge zone in the housing;and (h) recovering the treated aqueous surfactant solution from thedischarge zone of the housing for recycle to the apparatus.
 222. Themethod of claim 221 further comprising the steps of:prior to step (h),(i) passing the treated aqueous surfactant solution from the dischargezone of the housing to the contaminated solution storage tank; repeatingsteps (c)-(g) and (i) until the treated aqueous surfactant issubstantially free of oils, particulate matter and dissolved heavymetals.
 223. The method of claim 221 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone.
 224. The method of claim221 further comprising the step of:passing the heavy sludge from thehousing to a disposal container.
 225. The method of claim 221 furthercomprising the step of:skimming the light sludge from the housing; andpassing the light sludge from the housing to a disposal container. 226.The method of claim 221 further comprising the step of:withdrawingsolids remaining in the contaminated solution storage tank from thecontaminated solution storage tank and passing the solids to a disposalcontainer.
 227. The method of claim 221 further comprising the stepof:withdrawing solids remaining in the apparatus from the apparatus andpassing the solids to a disposal container.
 228. The method of claim 221further comprising the steps of:monitoring the amount of thecontaminated aqueous surfactant solution accumulated in the contaminatedsolution storage tank; and selectively passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank to the housing when a predetermined amount of contaminatedaqueous surfactant solution has accumulated in the contaminated solutionstorage tank.
 229. The method of claim 221 further comprising the stepsof:injecting a volume of treated aqueous surfactant solution recoveredfrom the discharge zone of the housing into the apparatus at asufficient pressure to flush the apparatus; passing the flushing aqueoussurfactant solution from the apparatus to the contaminated solutionstorage tank; and passing a volume of the treated aqueous surfactantsolution suitable for operating the apparatus recovered from thedischarge zone of the housing to the apparatus.
 230. The method of claim221 further comprising the steps of:operating the apparatus; andconcurrently passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing such that the apparatus is operating while thecontaminated aqueous surfactant solution is being passed through thehousing.
 231. A method for recycling a contaminated aqueous surfactantsolution of an apparatus, comprising the steps of:(a) passing thecontaminated aqueous surfactant solution from the apparatus to acontaminated solution storage tank; (b) accumulating a volume of thecontaminated aqueous surfactant solution in the contaminated solutionstorage tank; (c) selectively connecting a portable housing having afluid inlet and a fluid outlet to the contaminated solution storage tankand a treated solution storage tank such that the fluid inlet of thehousing is in fluid communication with the contaminated solution storagetank and the fluid outlet of the housing is in fluid communication withthe treated solution storage tank, the housing having a mixing zone, aquiescent zone and a discharge zone; (d) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing via the fluid inlet;(e) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone in an amount sufficient so that large air bubblesare formed in the contaminated aqueous surfactant solution in the mixingzone; (f) introducing water into the mixing zone so that the watercontacts the large air bubbles formed in the contaminated aqueoussurfactant solution in the mixing zone and substantially reduces thesize of the large air bubbles in the contaminated aqueous surfactantsolution in the mixing zone; (g) passing the contaminated aqueoussurfactant solution from the mixing zone into the quiescent zone wherethe contaminated aqueous surfactant solution is separated into an upperlayer containing light sludge, an intermediate layer constituting atreated aqueous surfactant solution and a lower layer containing a heavysludge; (h) passing the treated aqueous surfactant solution from thequiescent zone into the discharge zone of the housing; and (i)recovering the treated aqueous surfactant solution from the dischargezone of the housing for recycle to the apparatus.
 232. The method ofclaim 231 further comprising the steps of:(j) connecting the dischargezone of the housing to the contaminated solution storage tank such thatthe fluid outlet of the housing is in fluid communication with thecontaminated solution storage tank; (k) prior to step (i), passing thetreated aqueous surfactant solution from the discharge zone to thecontaminated solution storage tank; (l) repeating steps (c)-(h) and (k)until the treated aqueous surfactant solution is substantially free ofoils, particulate matter and dissolved heavy metals.
 233. The method ofclaim 231 further comprising the step of:introducing a chemical treatingagent into the contaminated aqueous surfactant solution prior to thecontaminated aqueous surfactant solution being introduced into themixing zone.
 234. The method of claim 231 further comprising the stepof:selectively passing the heavy sludge from the housing to a disposalcontainer.
 235. The method of claim 231 further comprising the stepof:skimming the light sludge from the quiescent zone; and selectivelypassing the light sludge to a disposal container.
 236. The method ofclaim 231 further comprising the step of:selectively passing solidsdisposed in the contaminated solution storage tank from the contaminatedsolution storage tank to a disposal container.
 237. The method of claim231 further comprising the step of:selectively passing solids disposedin the apparatus from the apparatus to a disposal container.
 238. Themethod of claim 231 further comprising the steps of:monitoring theamount of the contaminated aqueous surfactant solution accumulated inthe contaminated solution storage tank; and selectively passing theaccumulated contaminated aqueous surfactant solution from thecontaminated solution storage tank to the housing when a predeterminedamount of contaminated aqueous surfactant solution has accumulated inthe contaminated solution storage tank.
 239. The method of claim 231further comprising the steps of:injecting a volume of treated aqueoussurfactant solution recovered from the discharge zone of the housinginto the apparatus at a sufficient pressure to flush the apparatus;passing the flushing aqueous surfactant solution from the apparatus tothe contaminated solution storage tank; and passing a volume of thetreated aqueous surfactant solution suitable for operating the apparatusrecovered from the discharge zone of the housing to the apparatus. 240.The method of claim 231 further comprising the steps of:operating theapparatus; and concurrently passing the accumulated contaminated aqueoussurfactant solution from the contaminated solution storage tank into themixing zone of the housing such that the apparatus is operating whilethe contaminated aqueous surfactant solution is being passed through thehousing.
 241. A method for recycling contaminated aqueous surfactantsolution from a plurality of apparatus, comprising the steps of:(a)providing each of the apparatus with a contaminated solution storagetank which is in fluid communication with the apparatus; (b) selectivelypassing the contaminated aqueous surfactant solution from each of theapparatus to the contaminated solution storage tank in fluidcommunication therewith; (c) accumulating a volume of the contaminatedaqueous surfactant solution in the contaminated solution storage tanks;(d) selectively connecting a portable housing having a fluid inlet and afluid outlet to one of the contaminated solution storage tanks such thatthe fluid inlet of the housing is in fluid communication with thecontaminated solution storage tank, the housing having a mixing zone, aquiescent zone and a discharge zone; (e) passing the accumulatedcontaminated aqueous surfactant solution from the contaminated solutionstorage tank into the mixing zone of the housing via the fluid inlet;(f) introducing air into the contaminated aqueous surfactant solutionprior to the contaminated aqueous surfactant solution being introducedinto the mixing zone of the housing in an amount sufficient so thatlarge air bubbles are formed in the contaminated aqueous surfactantsolution in the mixing zone; (g) introducing water into the mixing zoneof the housing so that the water contacts the large air bubbles formedin the contaminated aqueous surfactant solution in the mixing zone andsubstantially reduces the size of the large air bubbles in thecontaminated aqueous surfactant solution in the mixing zone; (h) passingthe contaminated aqueous surfactant solution from the mixing zone intothe quiescent zone where the contaminated aqueous surfactant solution isseparated into an upper layer containing light sludge, an intermediatelayer constituting a treated aqueous surfactant solution and a lowerlayer containing a heavy sludge; (i) passing the treated aqueoussurfactant solution from the quiescent zone into the discharge zone; (j)recovering the treated aqueous surfactant solution from the dischargezone in the housing for recycle to the apparatus; and (k) repeatingsteps (d)-(j) for the contaminated solution storage tanks of eachapparatus.
 242. The method of claim 241 further comprising the stepsof:(l) connecting the discharge zone of the housing to the contaminatedsolution storage tank such that the fluid outlet of the housing is influid communication with the contaminated solution storage tank; (m)prior to step (j), passing the treated aqueous surfactant solution fromthe discharge zone to the contaminated solution storage tank; (n)repeating steps (d)-(i) and (m) until the treated aqueous surfactantsolution is substantially free of oils, particulate matter and dissolvedheavy metals.
 243. The method of claim 241 further comprising the stepof:introducing a chemical treating agent into the contaminated aqueoussurfactant solution prior to the contaminated aqueous surfactantsolution being introduced into the mixing zone of the housing.
 244. Themethod of claim 241 further comprising the step of:selectively passingthe heavy sludge from the housing to a disposal container.
 245. Themethod of claim 241 further comprising the steps of:skimming the lightsludge from the quiescent zone; and selectively passing the light sludgeto a disposal container.
 246. The method of claim 241 further comprisingthe step of:selectively passing solids disposed in the contaminatedsolution storage tank from the contaminated solution storage tank to adisposal container.
 247. The method of claim 241 further comprising thestep of:selectively passing solids disposed in the apparatus from theapparatus to a disposal container.
 248. The method of claim 241 furthercomprising the steps of:monitoring the amount of the contaminatedaqueous surfactant solution accumulated in the contaminated solutionstorage tank; and selectively passing the accumulated contaminatedaqueous surfactant solution from the contaminated solution storage tankto the housing when a predetermined amount of contaminated aqueoussurfactant solution has accumulated in the contaminated solution storagetank.
 249. The method of claim 241 further comprising the stepsof:injecting a volume of treated aqueous surfactant solution recoveredfrom the discharge zone of the housing into the apparatus at asufficient pressure to flush the apparatus; passing the flushing aqueoussurfactant solution from the apparatus to the contaminated solutionstorage tank; and passing a volume of the treated aqueous surfactantsolution suitable for operating the apparatus recovered from thedischarge zone of the housing to the apparatus.
 250. The method of claim241 further comprising the steps of:operating the apparatus; andconcurrently passing the accumulated contaminated aqueous surfactantsolution from the contaminated solution storage tank into the mixingzone of the housing such that the apparatus is operating while thecontaminated aqueous surfactant solution is being passed through thehousing.